How about rice, lentils, onion, and seasoning sauce (curry) of your choice?
I have never really liked hobo dinners that much, but that's likely because I'm not a potatoes kind of girl. Sounds better when you change that to rice, but I've never cooked/reheated that in a foil packet over the fire before.. you might want to test a couple recipes out at Hueston Woods beforehand.
I do like summer veggies cooked in foil on the grill, though. Yellow squash, zucchini, peppers, tomatoes.. I would probably cook these in a packet on their own and another packet for rice/lentils/beans.