I put empty pop cans on teh quilt. They'd fall off and the cat didn't like the noise. I found if I left a quilt on the frame for 3-4 days, he'd get up on it. But if I got it done and off the frame sooner, he left it alone.
I had set my frame up in the dining room and could not close it off. Was major motivator to building a new home for the LA.
BTW - so far I have ended up with short backing twice. I watched a video about adding to the back without taking the quilt off the frame, and it worked very well. Basically you flip up the batting and quilt, and then pin the new section to the underside of the backing - right sides together. I normally overlap a few inches so I don't have to worry about the seam allowance. With channel locks on (or a clip) you use the LA to sew the two backing sections together. Then you unpin the short backing, trim the excess, and pin the new backing and roll it up and finish the quilt.