Well, lets see if I can answer your questions. First, the rack behind the cab is sitting on an 75 gal fuel tank, and it holds 8 jerry cans and a cargo box. The fuel tank works well as a set back spacer for the camper. This allows the front of the camper cabover to be right at the front of the trucks cab, and not hanging way past the windshield, you have to remember how small a dueces cab is. It goes without saying having a lot of fuel is always a good thing.
I had to set the camper up a bit off the floor of the truck to get the cabover to clear the trucks roof. I wish I had made it a bit taller. A 2X4 ladder frame laying on the floor of the bed is just fine. This will space the camper up high enough and allows you to build into it supports between the bed side rail and the sides of the camper at floor level to keep the camper frpm shifting side to side while moving. Then all you have to do is secure it down to the bed floor. If the camper will allow you to, four bolts through the floor of the camper and then through the bed is best. I could not do that with mine and had to use chain mounts on the side rails, works O.K. but not as good as nuts and bolts. If you don't have a fuel tank behind the cab, remember you will have to build spacer supports at the front of the camper to the the front of the bed, like the side supports ( note, these will have to be stronger to hold the camper in place when stopping hard. But it will afford you more cargo space.
As to getting the camper off and on. I put mine on with a crain, and there it stays. ( poor mans M-109) I have found that the best I can find to remove it for an off/on set up would be a platform with some sort of rollers, built to the height of the bed that you could wench it out, and push it in. The short comming would be, if you have a plumbing that extends through the floor of the bed and floor of the camper, this would have to be removable also ( boy, that sounds like real fun )
I wish I had some photos of the build up, but they were lost. If you get into building on of these, I hope you have as much fun as I have had. Ever unit will be different and better for some reason. Best of luck.Take lots of photos,
but don't lose them! Looking forward to see what you come up with.
Unclemikey