I am in the same situtation. My daughter is allergic to dairy, peanuts, and beef. We avoid all nuts. I just have continued to feed my daughter grains because I think that outweighs the alternative. I think oat flour would still be better than other things though. I would not try coconut because it is still a tree nut if you want to get technical. If your child does coconut in other things then it might be fine, but I try not to be too brave with testing things out. Lesson learned the hard way:(

I'm no expert but my first thought was teff flour. Although still a grain, it is gluten free. Another option (again not paleo but better than a gluten flour) would be garbonzo bean flour.

That Paleo Mom article is a good one. I plan on buying some plantain chips to make plantain flour soon!

She's doing a whole series and it's so helpful! There's also one on leavening and fats and another on binders.