I found a site where one can obtain an owners manual for a Sunrader. I paid $25.00 US for it. It has schematic drawings of wiring system, flooring, heater etc. It looks like it may be a shop manual. Attached is a photo from it showing the floor construction.
https://www.ioffer.com/i/sunrader-rv-motorhome-operations-ac-furnace-manuals-192448328