Writing paleo would probably be confusing. I would probably just put gluten-free. You'll likely still end up with some rice or a potato, but that's not a huge deal and you certainly don't have to eat it. You could also add low-carb if that's really, really important to you, but I'd probably just stick with gluten-free. It will be less confusing for the catering staff, after all, it's only one night.

If eating the way you normally eat is something you don't want to stray from (I know I wouldn't), just be specific with your requests. I often tell people what I DO eat , as that seems more helpful than listing what I don't.

When I had to do things like this, I always put "gluten-free". Having celiac disease, it had to be a hard-and-fast rule. Sometimes I'd also put "no soy" just to be safe. Like Kewpie above, I'd say that you may end up with some non-paleo things, but for one night in moderate amounts you should be alright.