I've haven't yet done a multi-day hike in my Vibram Sprints, but I've hiked for several hours in them in sandy and rocky terrain. They've held up well in that for a year of use.

I suggest checking out this website: Adventure in Progress. Damien has been through just about every minimalist hiker that's available in the USA right now (except perhaps for custom-made shoes) and he's reviewed most of them. He and his family do multi-day hikes often and he's a minimalist shoe guru. If he doesn't have a shoe review listed on his website, you might contact him (via the website) and ask him about a specific shoe if you're curious.

Have you thought of making your own moccasins? ;)

Your foot has great lateral stability if your shoe doesn't take it away.

There are a lot of anecdotal reports of VFF holding up extremely well for trail running. It is hard to know from your description, but I doubt the outdoor school would be as tough as a marathon through the mountains which the KSO's reportedly handle just fine. If you want something a little more rugged you could get the VFF trek. You could also bring some sewing equipment just in case. You could also bring a pair of (cheap home-made) huaraches as a cheap back-up/alternate, although they can have problems with lateral movement.

Your biggest problem could be "proper size when worn with two pairs of socks".

I do a decent amount of backpacking.

I have done a 2 day trip in my Feelmax Osmas. My brother wore his Vibram KSOs. It was fine for both of us. In fact, my feet felt BETTER than they do after a day of boot hiking. My only problem with the Osmas was that the flat sole (thinner than Vibrams) made it VERY hard to climb when it started raining. We had bushwhacked in about 2 miles from the trail, to get to a lake. It started raining in the morning, and we had to go uphill with no trails. He had an easy time of it, and said the Vibrams made the climbing pretty easy. I was slipping all over the place, however.

A note about backpacking - the heavier your pack is, the more support you feet will need. I would not suggest minimal footwear unless you are also a minimal backpacker (20lbs including food and water, is usually the limit for "ultralight"). My pack is usually 18lbs without food and water. If you're closer to 30lbs, then get shoes with real ankle support - a roll to the side with that much extra weight can injure you VERY badly.

The other Vibram hiking thing that's important to bring up: stubbed and broken toes. It's very easy to do (since the rain trip I mentioned, my brother has broken 2 toes hiking in Vibrams). This could hamper your ability to continue walking.

Bottom Line: Don't do it without experience. Go out a few times before the event to get a feel for it. If it's not your bag, look into either New Balance trail running shoes, or a nice pair of Merrels (my current favorite)

The KSO Trek will give you much better traction when hiking than the KSO. I strongly recommend them.

The best thing to do is a few field tests while wearing your VFFs. Head out for a few long hikes. Make sure to carry approximately the same amount of weight in your backpack as you'll be carrying in August.

Start out with a short hike or two; maybe 2-4 hours. Work your way up to 6-8 hours. Once you've done that, try a 6-8 hour hike 3 days in a row. You'll be able to tell very quickly whether or not VFFs are a good idea.

Good luck!

Have a look at http://www.inov-8.com/

I use them for survivalruns (see http://www.youtube.com/watch?v=8ACRTLMunEA) but I've also walked across the 'hardangervidda' plateau in Norway (w/ backpack). I have an old pair of Terroc 330's.

I went for these (The North Face Men's Hedgehog 2 Gore-Tex® XCR® Shoes) they're pretty lightweight 'speed-hiking' shoes with vibram soles and goretex lining. The spec I was looking for was light shoes suitable for hiking (hence waterproofing and vibram sole), but with very little need for anything robust, since I'm just hiking around Britain's very clement landscape anyway. They certainly fit the bill, more durable than trainers, but lighter. Certainly they bear up to the pounding they receive as well as my hiking boots and better than some winter/work boots I tried before, but they're also light enough for me to run or go to the gym in.

There are lots of equivalent sorts of footwear on that website or by the same brand.

I've done about 1500 miles of the Appalachian Trail, and I use trail runners. I just got back from a hike in Tennessee and I ran into dozens of (potential) thru-hikers and saw nobody in VFFs. I was kind of surprised. Trail runners are now even with boots among the long-distance hikers I saw. Goodness knows they dry out a lot faster, and that's important if you're in a temperate rain forest!

I don't carry a heavy load though. My pack with 5 days of food and 2 liters of water weighs in at 21-22 lbs.

IME "ankle support" will not keep you from rolling your ankle, in fact, I think the inflexibility of having your ankles held in one place makes the injury (if there is one) much worse. If you're hiking off trail, there's plenty of opportunity for crummy footing, I'm sure.

One of the minimalist-shoe-guy reviews is for the Nike Free. I've tried them (including their trail version), and they suck for hiking. You slide in the shoe on a sidehill, which is serious bad news. I experienced this problem even without a pack!

Regarding another trail ergonomic thing: I sleep in a hammock, and that used to stand out. Now there's so many hangers that's not even notable.

I would at least do a shake-down backpack over a weekend where I hiked big miles on two days back-to-back. If you're going to have problems, you will probably see at least the beginning of them on that weekend.

I work for a online outdoor retalier www.travelcountry.com. We fit loads of people for backpacking and hiking.

First off, I'm a VFF wearer through and through. I run, walk, and hang out in them, but when it comes to hiking I choose carefully what shoe to wear. If I'm carrying little or no weight I would wear Vibrams in a heartbeat, but if like you say, 20-25 pound pack, Vibrams in my opinion would not be a good choice.

When you carry weight on your back for hiking you need shoes that will give you support and comfort because there is more weight on your spine, legs, and ankles. Imagine your body as a compression, the more weight you put down the more force is extended onto your legs and especially feet. If you don't have the support for you foot you will start to have lots of pain in the soles of your feet as well as lower back pain. Also firm footing is important so you don't twist your ankle when additional weight to your body is added, therefore making your center of balance different then usual.

I would suggest ideally a light hiker (a low is fine due to the small amount of weight), or a the least a trail runner. This would give you enough support in the sole, though not the best support in the ankles, but many light hikers nowadays hike in these.

Some of my favorite choices are:

Lowa Renegade GTX lo: http://www.travelcountry.com/shop/lowa/day-hiking/lowa-renegade-gtx-lo-mens.html

Lowa Jannu Lo: http://www.travelcountry.com/shop/backpacking-boots/lowa-jannu-lo-mens.html

Saloman XA Pro 3D Mid GTX: http://www.travelcountry.com/shop/backpacking-boots/salomon-xa-pro-3d-mid-gtx-ultra-shoes-mens.html

BUT, if you are set on Vibrams, go with the Treks. They have the most rigged sole, so it would give you the most support out of the Vibram line.

You can email me at: jwhitfield@travelcountry.com if you have anymore questions.

-John Whitfield Internet Assistant Manager & Marketing Specialist Travelcountry.com