I like all the ideas presented so far. My thought was also to put something over the bed. If you quilt big quilts, that could be a table, maybe with removable legs, that extends the space behind your sewing surface to support the quilts. Another possibility is to stand the mattress up against the wall and put the frame in the basement or elsewhere until needed.
I recommend you get the book "Dream Sewing Spaces" by Lynette Black. That is one valuable book! It will give you tons of ideas. Here is a link:
http://www.amazon.com/Dream-Sewing-S...+sewing+spaces
Cricket