Good Morning. I have same problem for very large quilts.
I bought a large vinyl flannel table cloth, lay in on carpet flannel side down.
Adheres to carpet very well. Also when new cloth I run it in my dryer first, low temp, to get rid of wrinkles. Watch it carefully so not to get too hot. Use safety pins to hold quilt down smoothing all the way. Works pretty well for me and not so hard on the knees.
A Helper would be good. I don't have anyone to help so it takes longer.