Hey Kimberly I have the same trouble with my Cali king which is on the floor... the idea I had last year was a king sized tapastry like this one:
http://www.rockstarhq.com/tapestries.htm
then sewing a king sized sheet to the back and stuff a down comforter in side... or use the bulk cotton batting and make your own. This is what I am planning on doing for our bed... as soon as I can that is.

Right now we are using a nice cali king sheet for a cover and using smaller blankets underneith.
Love Val