Unless you're missing parts, the conversion is pretty common.... the seats and backrests lay flat.... there will be a six inch gap at the aft end of the bunk between cushion and backboard. My boat came with a small bolster type cushion that slips into the gap.... and that's the end I put the pillows on.... You can be creative....or go to a fabric store and purchase a piece of foam to make a spacer.
A single air mattress will fit quite well in the space.... I just laid it right on top of the cushions....... pretty comfy, but when it crapped out I did not replace it.... the cushions are not as deep and soft as I like.... but interestingly I have become used to its firmness. I lay an additional 1 inch foam mattress pad over the cushions.... rolling it up with the bedding and stuffing it all in the vee berth when I put the table up.
