I would recommend that you do it in sections.
Put a little more than 1/3 of your batting in the middle of the top and bottom and sandwich as you usually do. Quilt that section to within a couple inches of the end of the batting. Add your next 1/3 section to one side and sandwich that. Don't overlap the batting, butt them together. I spray baste the edges as well as I can and then quilt that section and do the final 1/3.
It's much easier to work with in that small a throat.