I filled in voids in the floor frames with rigid insulation. ☹️No pic but one can imagine the pink stuff sliding in. It was then that I realized I had not pulled any 12 volt wire through for the rear plug I had planned. argh!
It was not difficult and soon all was ready to glue: floor, joists, and undercoated plywood together, carraige bolts poking through the 3 sections, extending through the trailer beam holes as planned.
A sanding job preliminary to a coat of finish rounded out todays build
Note the floor is set back from the trailer edge. My design has the wall securely on the underlayment and screwed/glued into the side of the floor, maximizing strength and connection.