[Gary Dillard]

If you use the kitbot chassis, here's a quick method I found year's ago on CD (so I can't take credit for it) that we have been using for years, although to install the tee nut you should really do it from the back side (inside the fabric); there may be an alternate nutplate you can secure to the face of the plywood or you could use lag eyebolts that thread into the plywood. You will need (per bumper, one for each color) two 1/4-20 Tee nuts and two 1/4-20 eye bolts ~2 inches long, (per bumper) two 1/4-20 x 2 inch bolts, two 1/4 fender washers, and two 1/4-20 wingnuts

1) Pick 2 holes in the chassis that are clear for attaching the bumper, spaced sufficiently far apart to give you some good wheel base. The holes are on 1 inch centers so I makes it easy to transfer the measurement to the bumper.
2) Put the bumper next to the chassis and determine the height needed to put the bumper in the correct zone (between 2 and 10 inches from the floor)
3) Mark on the plywood the center of the 2 support holes, about 1/8th inch above the frame, then drill holes in the plywood to clear the tee nuts (I think they are 5/16, could be 3/8).
4) Install the tee nuts into the plywood from the back (fabric) side and thread in the eyebolts
5) Put the bumper against the frame and adjust the eyebolt lengths so they line up with the holes in the frame. Drop in the bolt and fender washer, and secure from the bottom with a wing nut.

Makes for a simple, adequate attachment and pretty quick changeout.