What I did with my POPUP was to add a three-inch MAGIC FOAM topper to both tent bed ends... Made all the comfort difference in the world.
Not sure what it would do for making your used mattress more hygienic safe for you to sleep on. If that is a real concern and you are having trouble replacing it with a new one try finding a plastic bag to slip the mattress in and use the three-inch memory foam topper on top of that ??? You could probably get a plastic bag at almost any mattress place.
On my trailer the three inch foam topper just meets up with the roof when lowered down into travel mode. Anything thicker would end up being depressed when the roof is lowered.
Keep in mind when you are searching for the right size that the trailers use what is called RV SIZES which are smaller than the residential mattress sizes. Make a measurement of your POPUP mattress size to get the correct size before buying one.
Also alot of POPUPs may have the built-in electric heater pads. One of my trailers has this...
Roy Ken
