I have the Brakemaster, which is air operated off the bus braking system. It does attach to a mounting plate on the floor and the brake pedal, but once you have that stuff installed in the Jeep, putting in and taking out the brake actuating device (basically and air cylinder) only takes about a minute.

It was my choice because I can use it in multiple vehicles although the MG and Air Force One are better systems, but unfortunately are permanently installed in the toad.