We bought a 2 inch memory foam topper for our bed from Sams Club for $99 a couple of weeks ago. Four pound memory foam. We love it and sleep better than we have in a couple of years. So, bought another one, queen size, and custom cut it to match the RT twin bed cushions. Then, wrapped it with some material and simply pinned the material on the bottom side and placed the memory foam pad on top of the existing RT bed cushions.
One queen equals two RT single beds with a couple inches left over to trim.
My hip bothers me after a strenuous day of hiking (can you spell AGE?) and this is really going to be a great answer. Did a google search for "cutting memory foam" and found that the best way to cut this stuff is with an electric kitchen knife. I was frankly surprised at just how well that worked. Couple of youtubes when you google that show how it is done.
PSW
2013 Phoenix Cruiser 2350
2014 Jeep Cherokee behind it
and a 2007 Roadtrek 210P for touring