I disagree.
As posted before, if I fill thru the outlet valve, (no choice) that will defeat the float shutoff that is attached to the 2" acme thread filler valve that is normally used by filling stations.
And where do they get 20% ?? My tank in question is a 29 gal tank, stamped right on the metal plate, but it holds only 18.2 max when its bone dry. So I'm sure not worried about over filling. So maybe by gravity filling, I can finally get a full tank of propane,....or at least 23.2 gals ?? Get 2 birds w/ 1 stone ?? This is sounding better all the time.