It's late February. Time for a Lightly-Used Mattress Party!
Keep flipping them til you find a clean side! No permanent indentations! Just the faint odor of power failure sleepovers and your last three cats!
When it's all over, leave the mattresses at the end of the driveway with hand written “Please Take Me” signs on them and tell relatives sorry, they must be mistaken, you've never had a guest bedroom.
Then start planning that new Den/Lecture Room!