Erik, I was/am a close-to-elite level swimmer with similar work capacity needs as rowers, so I'm not sure what level youre competing at or want to compete at, but here's my advice:
When I first started to go paleo I made a mistake of not ensuring that I was eating enough carbs. Whatever people say about it being possible to be in great shape low carb, it's not optimal for 99% of people who are putting in tons of kms of training and working at a very high intensity. If you want to be the best you can be, make sure you are eating lots of potatoes/sweet potatoes/white rice etc. especially after workouts or when you are training twice in one day. I think part of my problem was that the Paleo Diet for Athletes would tell you to just eat Sweet Potatoes or other random tubers like turnips and so I would just have like 2 sweet potatoes a day and some fruit and think I was fine. From personal experience and the experience of others, I guarantee you that you will be much better off consuming white potatoes and white rice if it helps you get more carbs in. Don't forget that a lot of the paleo advice is geared towards people who need to lose weight/get healthy, not going from healthy to being a total monster.
I also think, again from my own experience and my own understanding of how your body uses various forms of sugar/carbohydrates, that this is going to be much more helpful than trying to eat tons of fruit just because fruit is "more paleo" in some way. I limit my fruit intake, to be honest, and feel much better than when I didnt.
It can also be hard to get enough calories eating paleo if you are really trying to train at a high level, so that's another place where white rice and any form of potatoes can be helpful. Also, whey protein is great when you think you might benefit from more protein, or fast-absorbing protein at certain times. I have not experienced or heard of any negative effects of that, despite some "it's-not'paleo!" outcries.
Bottom line: Put performance above historical reenactment theory.