If you decide to go the motel route, Ed & Kay @ Springview Fly Shop as well as Larry @ Larry's Sporting Goods both keep a few rooms open throughout the winter.
I personally always stay in my 5th wheel when I winter fish, but only becuase it is located not a mile from the park year round. If I didn't have a perm site, I agree with the others in that it is just as cheap to stay in a motel.
JR