Well, I looked into the popup but its just not what I want, there are only a few models with showers and true toilets most have porta pottys. I want to be totally comfortable when i'm out. They make a hybrid with solid walls that lift up to create a full height camper but none in the 8x8 footprint range, so back to the drawing board.
I contacted TJ's trailers in Ogden and they said they would build me what I want on the front, so I am drawing it up and faxing it to them for a quote, we will see what happens with that.
I like your idea Bart about just setting an old fifth wheel on the frame and mounting it down, it might take forever to find the right one though, I need one with no more than 8 feet from the step up part of the trailer. I have been in close contact with several of the bigger RV salvage yards in Phoenix and LA, they know what I am looking for. The trailer I bought was a 5th wheel trailer that had caught on fire and burnt the roof off so it already has the mounts for storage tanks, propane, etc.
Before I bought it I contacted the manufacturer of the RV for the same reason that meat had issues with, I was concerned with the frame and axles being modified to do what I want it for, they gave me the number of the frame manufacturer (the RV company has all the frames built by a different company) I told the guy what year, make and model the RV was, he looked it up in their book and told me what size and type of steel they made it out of. After explaining to him what I wanted to do with it he assured me it would be fine for that. He said they also build flatbeds from the same basic frame and axles that other company's put there own name on. Here is a link to what the RV was before,
http://www.keystone-bigsky.com/?page=detail&year=2008&model=360REQ you can see from the spec page it was a pretty heavy trailer to begin with the total weight they say it could be loaded was over 15000 pounds so I don't think I will have any issues with it. I will be putting some angle reinforcement on the outer edges anyway, then putting a good solid deck on it. The width of the frame rails on the trailer is right at 6 feet so my tires should ride on the rails for the most part......hey it was only a thousand bucks anyway right