You are car-camping, right? (Or car-cooking?) And is this in the States?

If so, your best bet is a big propane tank and multiple stoves. Don't underestimate the challenge of cooking for 25, which is difficult even in a fully stocked kitchen.

Personally, I wouldn't attempt such a thing without (at a minimum) one powerful burner to use as a "boiler" (such as this Woodland Power Stove) AND something like a Coleman double-burner. Cabelas also sells some heavy but high-output propane burners, I think.