I have this problem as do others in classes I go. Take the quilt and divide into manageable sizes to fit any suitable surface you are comfortable with. Kitchen units ar just the right height to stand at. Usually your size of qiuilt would go into 3 long stripes . We don't sew them together on the piecing section leave to size. Now sandwich these smaller sections And then quit. Take section 2 and do exactly the same . Join the piecing sections of these 2. Use sewing machine to sew pieces then turn to back lay flat trim batting to fit and join by hand then join the backing pieces some of the group. Use sewing machine to make it look like quilt in the ditch, I prefer to hand sew to make the join invisible.
Do the same to 3 and whole quilt done.look at Angie quilts . Blog site.