There are some tricks for taking in fullness as you are quilting on a LA. Some use starch. They spray the area while it is on the rack and as the starch dries it takes in some of the fullness.
There was a product out there called Glide 'n Go. It was a clear oval of plexiglass you placed around the hopping foot and it smoothed out fullness as you quilted. Unfortunately the website is no longer active so i don't know if they went out of business.
Personally I would try the starch.