[bigbeezy]

we used those fanged nut things to hold bolts in the side of the bumper. Then cut out a key-hole shape in the frame so that the top of the bolt could slide in and then fall down tightly into place. This proved to be very easy to mount/unmount the bumpers.

For our rear bumper we went with drilling 2 holes in the 1x2 that forms the rear part of our frame. then we mounted 2 small pieces of angle to the bumper and used I-bolts to hold the bumper in place.

EDIT: We used epoxy to hold the fang nuts in the wood and except for one they all held. loosing the 1 was no big deal since we had 3 mounting points and it was the middle one.