I used one for years! Did all sizes of quilts on it...even king size.
There are two things you will need to do to be able to quilt the borders...
Either leave about 6-8" of backing and batting all the way around so that can be clamped leaving the borders out far enough away from the frame to quilt...or you can cut 6-8" wide strips from an old sheet and pin them to the edge of your quilt and then clamp the strips of sheet to the frame...again, leaving your borders out away from the frame so you can quilt them.
HTH