Now that we had a flat spot, we needed a mattress. However that flat spot was oddly shaped.
We did not want to purchase a specially made mattress to fit so we scoured Amazon, Walmart and other sites for small mattresses that we might be able to squish into our space. Our choice was a Milliard Full-Size Tri-Fold Mattress.
The two main folding sections mostly fit on the platform with some squishing in the back 49″ wide section. We removed the two smaller foam pieces and cut one to fit at the passenger slider where we plan to usually get in and out. We slid the cut piece back into the mattress casing. The other piece we squish in at the drivers slider since we rarely expect to open that side.
With the mattress in place, we had a bed.