Sorry for the duplicate thread, could not figure out how to add the image afterwards, or delete this one.
Our original mattress was getting pretty tired, to the point that sitting up, we felt like we were on a sheet of wood, which is pretty much the case.
We were looking for an inexpensive replacement. Enter Ikea.
We went to Ikea and found that they have memory foam mattresses that can be laid right on top of a foundation, basically a box spring or a plywood foundation that looks like a box spring. Perfect for the sheet of Oriented Strand Board that serves as the foundation in the Escape.
The one we decided on was the Malfors Queensize, 60x79-1/2, $249.00. Perfect size for the Escape 19, except for the rounded back corners.
It is a high density memory foam firm mattress, about 4" to 5" thick with the covers on. One of the nice things is that the cover is two peices that zip together so they can be washed. So it is easy to remove the foam, and also easy to trim it for the back corners.
We unzipped the cover, folded it back, and layed the original mattress over it as a pattern. I marked the curves on the exposed foam of the new mattress with a Sharpie indelible marking pen.
So we wouldn't cut through the cover or the carpet under it, we put a cutting board under the foam, being careful that the new cover was folded back out of the way on the bottom.
I didn't have an electric carving knife, which I understand will cut foam very nicely, but a cerrated Cutco bread knife did the trick almost as well. I made several straight cuts straight down following the corner marks, and ended up with 2 nicely rounded corners.
When we zipped the covers back together, there is a slight baggy area in the back corners where the foam was cut away. Perhaps a skilled seamstress could fix that, but after we put it back in the trailer, it is not noticeable, and will not matter as far as we can tell.
It is pretty firm. Sitting up I can no longer feel the sheet of wood under it. We will try sleeping on it. If it is too firm, we will try putting the flapped out original mattress on top of it.
Will have a sleeping report soon.