As I understand it, if you have a GWL and submit the appropriate letter to the appropriate commander, COE will give you a letter, no proof or extraordinary reason like the NY case before SCOTUS.Hard to say if that's progress as the COE may be like NYC. Maybe this case heard before SCOTUS will change that.
Biggest PITA is that Lakes on the Chattahoochee are in one district, lakes on the SC border are in another, two commanders, two letters.