I machine quilted an oversize King Size quilt as a wedding present for my daughter on my little old circa 1955 straight stich Singer Sewing Machine summer before last. I cut the batting into three sections, spray glued one section, meander-quilted that one section (it was the left hand side of the quilt so that all that was under the arm of the sewing machine was two layers of fabric and at times, some of the batting. Once I had one section quilted, I sewed together and glued in the middle section, quilted that, and then the last section. It worked like a charm. The top and backing were all one full size piece, but without the batting, it fit under the head of my machine. It was not "easy", but it was do-able and going forward, I will do the same for any other large quilt. This may not help with this particular quilt, but try it with other quilts. It makes a difference.
Good Luck!