Hi Ryan, sounds like a lot of fun and adventure.

You will certainly get some good advice here. I will chime in on only one aspect...

Freeze dried food for 20 days you will only need to have a stove capable of boiling water like a jetboil, primus, optimus or msr. Have you experience with freeze dried meals? personally I can barely eat one, let alone only that for twenty days. Thus if you are certain about the freeze-dried, go with a canister stove as mentioned. Have fun out there!