Hello! I am researching mattress recommendations for a family member living in a studio apartment. The living/sleeping space is 11x11. After much research, a daybed with some sort of removable back support seems like the most viable option since this mattress will serve as both a bed and a couch. I’m seeking recommendations for a firm or very firm mattress (twin or twin XL) with sturdy edge support. Ideas for daybed frames would be very much appreciated. I’ve read that a frame with a back and arms would better than a platform. I would also appreciate suggestions for wedges and/or bolsters to create a couch-like back and couch-appropriate seat depth of 21-24" if that is appropriate for this forum. My family member will be spending the overwhelming majority of their time in this space and I’m hoping to make it as comfortable and functional as possible. Thank you very much in advance