There is a method for cutting the batting into 3 pieces that cuts down on bulk under the arm of the machine. First saw this described in detail in one of Debra Wagner's books. Marti Michell has a whole book out now on methods like this.
Basically what you do is cut the batting into 3 parts using a rotary cutter to make big S-shaped cuts (about 6 inches wide). Before moving the batting, use a Sharpie permanent marker to make registration marks on the cuts. That is, you mark a line through the cut every 8 inches or so. Also label the tops of the batting with right, mid, left. This makes it *much* easier later to line up the pieces exactly as they were before they were cut. The reasoning behind the S-cuts is that later on, after the quilt is used, the batting will not crease the way it might if it were cut in a straight line.
Layer the quilt sandwich with just the middle piece of batting, and baste that middle section as desired. (You can even spray baste if you are careful to cover up edges with paper first.) Machine quilt that middle section, leaving perhaps 6 inches on each side unquilted.
When finished with the middle section, lay out the quilt, peel back the top and backing, and re-attach one side of the batting. Wagner suggested hand joining with a tailor tack stitch, but most people use a wide and long machine zigzag to re-attach. These days you could also use a fusible to rejoin the batting pieces. Just make sure that you are matching registration marks and re-creating the original batting as it was first laid out. Once the batting is re-attached, smooth out the backing and top and baste them.
What this process does is greatly reduce batting bulk under the arm of the machine, making the quilt much easier to maneuver while machine quilting. No one knows you used this method after the quilt is finished, because the joins in the batting are invisible.
I know several people who have successfully done a large quilt on a domestic machine this way.