When visiting Trumpetguy's "Setting Sail" I noticed a temporary table that was set between the twin beds. Just the night before I had thought that something like this would be very handy for placing a snack, the tv remote or even a drink. In addition, this table/shelf could be used to hold a CPAP machine or similar item for those that need these things. During the day or for travel, the table/shelf is easily removed and stored under the couch/bed.
I believe that Trumpetguy made his out of a piece of wood, but, I had a fairly heavy piece of dark smoke Plexiglas scrap laying around, so, I used that. The rough dimensions are 20 x 10 inches, but, it could be made as necessary. Once the piece is cut , sanded and the edges rounded, it is simply "wedged" between the two mattresses to hold it in place. Bill