I'd just make 'em. I made these for my buddy's truck.....just kinda made stuff fit. Never made a back door for it though, but it did the job....
CRAP! I don't have pictures of histruck with them installed. I just used like trimmed down 2x2's in the stake holes, then some 1x6's or 2x6's going between the two stakes. yes they shook a little bit, you could make a crossmember on the front, and hinge and pin a rear gate to eliminate that shaking.