I actually suggested something very similar at my daughter's home. Small backsplit, with a storage area that was about 3' tall. She wanted some guest space and could
have had a roll out bed hosted there, with minimal work.
I wouldn't automate anything. Go low tech. Just some locking wheels, with a low platform. Simply pick up and move the front row seating, and roll out the trundle bed.
These suggestions don't make a lot of sense to those with homes with large square footage, but they often can really up a small home's game.