Pulling a 5th wheel RV trailer with a 1/2 ton.
Install a set of Timbren overloads on the rear and you will be fine.
9 1/4 rears are built just like a standard car rear axle. They do not use the axle tube as a bearing race. Not a "floater" rear by any means but strong enough with a normal load.
There are plenty of light weight modern trailers available...