After all the drawing and thinking on making a folding trailer, I decided to go with a simple plan -- get a trailer that is tall enough to stand in! Found a great deal on a 1966 Scotty Sportsman 13', got it home, and found that it was in pretty bad shape under the skin. It is now stripped to the frame, but will rise again from the rot. The features I like are room for a full-size bed, a small dinette, a porta-potty, and standing in the dropped floor. It is also short, and has the curves to make it stylish.
I am not "restoring" the trailer; I will rebuild it to suit my needs. One idea is to put a galley-ish feature in the rear end, to save dragging things out of the trailer to set up the kitchen. Take a look:
The countertops flip over from the front of each half door, and there is room for a cooler and other stuff inside (under the bed). Small items can be stored in the doors, and the cooking will be done several feet away from the trailer on a free-standing table.
First I have to work over the frame, and replace the wimpy torsion axle with a new, beefier setup. So, not in a rush, but at least I have started!
If anyone needs Scotty parts, I have a pile of 'em I won't be using, including the windows. (Got a deal on newer windows from a demolished camper.) About all that will reused is the frame and skin...