I have been reading this with great interest. Some time ago I sat down with paper and pencil and came up with my design for a "standy " as you call it. It would be built using the cargo trailer basic design.
The cabin would be 14 long x 6 1/2 wide x 6 high (interior) The entire camper would be aluminum. From the center line forward the roof would drop to 4 feet at the nose to have it pull with less wind resistance. There would be two 2 x 3 sliding windows in each side, fantastic fan in the roof, house hold air conditioner (5000 btu) mounted in the rear wall and would have a rear entrance door. Inside
would be a small kitchenette on the left rear side. A 2 x 2 shower/porta potty on the right rear side. The two bunks would be 30 in wide each mounted front to rear in the front with about a 12 inch isle way.
I already have a 3500 lbs torsion axle with brakes wheels and tires. I priced the 1 x 2 aluminum tubing and the skin which is not cheap. I have the shop and welding equipment to do it all. I then went to a local cargo trailer mfc company and ran my plan by the owner/engineer. According to him my plan is very doable. I want to check out what I can build it for compared to what the company would charge me to build the frame, skin the unit, installing the windows and door using my axle, wheels and tires. The difference in time and trouble may not be worth my doing the basic building of the frame and cabin. One other thing was that he said he would take care of assigning the VIN and Florida title. I would then take care of building the interior which would include the electrical, plumbing, refrigerator, microwave oven. cupboards, shelves and other storage. He is going to draw it up on cad and will get back with me as to weather he can do it within my budget which is $2000.00 for his part. Here's hoping..............