If you use 156sqr ft for a loose cord thrown into a trailer, which is the number I've seen thrown around, then 20x8x3.3+528/156+3.384 square?
My BIL lives east of you a bit on the other side of Atlanta in Canton, he's working up here by us right now though.
I have no idea which one of those works best, I've seen a few videos, but not many that worked great.
@farmer steve may have some ideas on it. Many of the places I've seen that sell a lot have a nice concrete pad and barricades to push up against at the back.