I've been given a tandem axle trailer frame. This frame was under a 26ft camping trailer. It is a lightweight frame with electric brakes.
It is designed to support a floor 8ft wide by 26ft long. Sections in the frame fall about 4ft apart.
The frame is probably too long, but the frame can easily be shortened.
Here is a design idea (not to scale ) for a cabin with back porch that could be built. The calliope could be mounted under the porch and protected from the weather.