22" wouldn't put much of a moment-arm on the frame, but how strong the
frame is, is the real question. 2" C- section? 4"? 6"? Supported at the
wheels and the hitch, or jacked-up around the perimeter in various
I'd say 22" doesn't seem like much of a gain, and if putting a footing
in IS an option, can you make it a lot bigger than 22"? Build as big as
you can get away with, and can afford.