So I found a solution to the problem.
We slept on the 2" foam on the floor and found it pretty comfortable.
We laid on the floor on the air mattress that came with the sofa beds and it wasn't too bad. A bit of falling together if you ran it with lower air pressure, but not bad. If you crank up the pressure there is no falling together, but then its a bit hard. And if you sleep further apart with lower pressure its not bad.
So the problem wasn't the foam or the air mattress itself. The problem is that the base the sofa beds create for them isn't firm enough.
So I cut 2 pieces of 7/16" OSB. One piece is 52 x 33". The other piece is 52 x 31, with the rounded corners.
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The OSB pieces fit nicely under or behind the sofa beds. Total cost is 2 sheets of OSB per bed, about $15, plus the time to cut them.
Problem solved ! Now the sofa beds sleep really well with the 2" foam mattress and quite good with the air mattress. We now have 2 good sofa beds for our guests. This has been a problem since we purchased the trailer 5 years ago. We are very happy to have this resolved.
I hope this helps someone.