Try rice cakes--not the dry packaged kind, although those are fine. I'm thinking more along the same lines as polenta--cook rice (shorter grain is going to have more sticky starch than longer grain--arborio will be particularly good), mix in any sauteed vegetables, beans or meats he may like. Shape into patties or cool in an even layer on a cookie sheet then cut into shapes. Fry these in a frying pan to crisp up the outside. I make these any time I have leftover risotto. Favorite additions in our household are sauteed onions, leeks, herbs, garlic, black beans, roasted red peppers, pine nuts, ham--but not all at once! And cheese, but that wouldn't work for your son.

I've never done it, but you may even be able to make these very thin, and use them like bread in a sandwich-like creation. You may need to add some additional thickener (cornstarch, tapioca, or guar gum, available at natural foods stores) to help them hold their shape.

Another thought--what about spring rolls (made with rice paper wrappers, not the egg/wheat wrappers used for eggrolls)? They are good either soft/fresh (wrap tightly in Saran to keep them from drying out) or deepfried, and are good cold. You can make a sweet-sour dipping sauce out of fruit jam or chutney (apricot or plum come to mind), vinegar and some hot sauce if that appeals.

Sounds like you've got quite a challenge on your hands, good luck!