sewnclog

Snooze2978; I have a longarm and my mom somewhere at one time heard this idea and I tried it; it works. Make some 'side leaders' like ones you connect your quilt to but these will be pinned on the sides or ends where the clips are. I made mine out of drapery or upholstery fabric for a sturdier leader; made a narrow sleeve on one long side and slide about a 1/2 inch dowl into the sleeve, the length of the sleeve. My end leaders are 6 1/4" by 16 1/4" with the sleeve on the 16 1/4 inch side. I just serged around mine, but you could finish them off nicely if you prefe. The end leaders are pinned to the ends of the quilt; backing and batting if possible, but sometimes I only have enough fabric to do the backing. Pin the long end without the dowl to the side of the quilt ends and clip the clamps over the dowls. I mark the quilting area (if using a pantogram - which is all I'm comfortable with for now) on the table with painters tape, so I don't overshoot the ends and hit the pins. It's worked excellently for me and eliminates the needs for an extra 6 inches of fabric on each side and the bottom. Yes it does take a little time to pin them on and remove them each time you roll the quilt but to me it's not a great big deal. The dowl rods also keep the sides consistently taut, so I have less an issue with wrinkles on the back because the entire side is kept ridged (for lack of a better word), rather than just the two areas where the clamps are placed; it puts consistent pressure or tautness on the entire sides.
I hope this makes sense to you - and the others who have longarm quilts. Because of the cost of fabric, I hated wasting that 12 inches of fabric on the sides. This has completely cut that out. And you can make the sleeve as long and/or as wide as you want. Good luck. Hope this helps your dilemma of needing a wider backing.