I cut out about 8 inches from the rear of the bed - if you look at the curved impression line on the side panels, I just made the front match the back. I didn't cut the bed with a vertical cut, but rather cut half way down, then over 4 inches, and then down the rest of the way. I figured that this would give it some inherent strength. The bed floor is made up of some nasty corrigated steel that I found on top of a barn, but I got the real old style that is curvy rather than angular. I actually bolted the tin directly to the frame.