We need to replace the king mattress in our fifth wheel. I would like a good quality one, but want to stay away from the high end memory foam and select a setting types due to weight. Just a good qual...
Be sure to check the actual size. In an RV, don't just assume a queen is a queen.
Early on we replaced the OEM mattress. Just went to a local mattress manufacturer. We went with solid memory foam, and they could cut that to any size we wanted. I think most cities of any decent size have an actual manufacturer of mattresses. It isn't rocket science, and as someone noted, markup is really high on them.