Sam
Bear in mind my only experience with trapping rabbits is back in my Boy Scout days (and I'm NOT going to tell how long ago that was) with box traps. So with that in mind feel free to take this with a grain of salt.
I've never heard of a foothold traps for rabbits but the first thing that jumps to my mind is if it works you'll probably need to beat the coyotes, bobcats, foxes, hawks, large snakes, and maybe local dogs (or whatever) to your trap.