I slept on the mattress that came with my 3575RL for a month or so, and wasn't happy. Didn't help that my previous bed was a topline H20 bed, used to the best. Gave the orig one away, and bought a new short queen foam mattress from
http://www.daysend.org/
It's been a bit over 2 months--I am very satisfied. They ship these all over the country, rolled into a box; had heard of them because they are horse people and make 'em for horse trailer living quarters too. I'm not associated in any way with this company, just thought it was worth passing on. They make the memory foam ones too, but I dislike those. Anyway, here's a little blurb from their site:
Our Original Pressure Reduction Mattress is the one that was specifically developed to reduce pressure points. It has 3 layers of foam including the patented die cut inner core that acts as inner springs and will adjust to each person’s individual weight. When your spouse rolls over, you won’t be catapulted off the bed!
Lynne