Where to buy an RV mattress like the bunk mattresses?

chracatoa wrote:
Wait, Walmart mattresses are 80x60 so they don't fit our short queen bed (maximum we can get is 77.5").Walmart link here.

You can cut them with an electric knife, but ours worked fine - they can be squeezed into a smaller space. We had a short queen in our Rockwood TT. It did make it tight when we had to raise the bed to get to the storage underneath, but we did that seldom, so it was no problem. The upside was that it did hold the sheets on there pretty well since it was so tight.