No reason to remove the mattress. "Storage" is in the mind of the beholder. Although I rarely have anyone sleeping up there it has become, as others have observed, a place for many soft things, extra bedding and for me a host of things that may be set away in transit and brought back down when set-up. I don't know if I would want to anchor anything up there per se. It is quite utile otherwise. I never wanted an entertainment center in the cab over for that very reason.