We had the same kind of problem with our Hunter Compact-II, that doesn't have any seating when the bed is made up.
Here's what we did:
We got an innerspring Futon mattress from IKEA, there are also foam ones that are much easier to cut. A true futon mattress is made to fold and doesn't leave a gap when flat like cushions might
We then cut the dining table in half and made the back 1/2 semi fixed in it's usual lowered place. The front 1/2 became a table for 2 with a new pole base etc.
If we want the bed, it's all flat and ready to go.
If we want a dinette we flip the front 1/2 of the futon mattress onto the back half, put the front half of the original table on it's pedestal, and put down a few pillows for seat cushions. We also made the table top so it will slide on it's base for easy of entry
If we want space to entertain and dance, we flip the back half of the futon straight up, and push the entire futon to the wall, making a full width couch (for friends).
Sort through this link to the second page and you can see it in several configurations.
Hunter Compact II Photos by advocateone | Photobucket
And YES, I had to cut down the innerspring futon, get the foam one for a Scamp
because you will have to cut the back half to fit the curved walls.
Almost forgot: We use storage bins, selected for exact fit under the bed, for clothing storage etc.