I see a lot of rv queen / short queen beds in the width of 60" and a short length of 75" opposed to a regular full size queen at 60x80.
I have seen people use a foam filler at the head of the bed and then use a regular set of 60x80 sheets on a 60x75 short queen bed when they have a filler in place.
The problem I have found in many rvs like certain Winnebago floorplans and some Airstreams is the bed they use is only 48" to 54" wide and in most cases there is no room to add a foam filler on the sides to make it wider. That's why I shopped for a floorplan with a full size 60W x 80L full time bed . I can buy any replacement full size queen mattress from anywhere if I need to replace it. I use a Serta Deluxe pillowtop at this time and find it very comfortable which is important to those that spend 1/3 of their life in a bed :).