There's a company called Heather's Choice that makes  a line of allergen-free backpacking foods. I have never tried any of them, but this may be a good place to start. 

https://www.heatherschoice.com/

Also, there's a company called Packit Gourmet that carries a pretty wide selection of freeze-dried "groceries" so you can make your own meals -- could be a fun way to come up with some of your own favorites.. Here's a link to their grocery list: https://www.packitgourmet.com/AllGrocery.html