I agree that it is probably the weight of the quilt that is the problem -- especially with that word "wrangle". The ideal would be to suspend the quilt:
http://www.jennoop.com/suspenders.html
This eliminates drag as you work. Meanwhile, if you can spread the quilt out over a larger surface, that will help.
The walking foot expects to be "fed" the quilt. If there is any tension on the quilt (for example, quilt draped over front of sewing machine cabinet), this will interfere with the ability of both the feed dogs and walking foot to move the quilt while forming stitches.