215WSK L-sofa: turning it into a sleeper

[Angelab56]

We have a FunFinder F-215WSK, with the outside kitchen and the sleeper sofa. It's a great camper for just the two of us DINKs (dual income no kids) but we *do* on occasion have a guest.

I'm looking for suggestions on either replacing the L-sofa with a sleeper sofa, or creating some kind of platform/cushion that can hook onto the existing sofa frame to make a bed. While it is possible to sleep on the L-sofa if you curl up or bend, it's not a restful night.