Effie,
My current build (ROUND TAIL) is on a 1965 Shasta chassis. If you're thinking of remodeling one, beware, that the factory chassis is way under-built and very short relative to the box on it.

The main support for the plywood structure is a hokey set of steel uprights in the front with an angled, 6-inch wide sandwich of steel strap that stands about 3 feet high. I torched it off and welded in a lot more steel floor support, plus I extended the chassis. (See photos on link below.)
Prem
My goal...
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...is to live in a trailer.