I quilt queen/king size on a Viking Sapphire 870Q and the setup that has made it a joy to machine quilt is the pulley type clamps hung from the ceiling.
http://pieceocakeblog.com/2013/09/22...pulley-system/. I have mine hanging from a normal height ceiling, ordered the clamps from Home Depot and got the "jacket cord pulls" from JoAnn's with a coupon. Had some leftover drapery cord from my roman shades that I used for the cords from the ceiling. Could not believe the difference...no more shoulder, neck pain and the quilt moves easily.