I would agree that Bering Buddies are easy to over-grease. IMO, they really only belong on boat trailers where a hot bearing hub is submerged in water and cools so quickly that water is drawn into the bearing cavity.
The answer to your question is to look very closely at the plate in the BB that has the grease fitting threaded into the center. That plate should be recessed deep into the BB. Observe it closely when you add grease and you'll see that it moves toward you and compresses a spring as more grease is added. Only add enough grease to cause the plate to move very slightly outward. In the boat trailer application, this spring maintains a pressure on the bearing and must be compressed far enough so it does not bottom out when the housing cools. If your RV bearings ever get submerged, you've got bigger problems than wheel bearings.
Dexter axles on my 2013 KZ Stoneridge are "Never Lube" permanently lubricated bearings just like cars and trucks have had for several decades!
Central New York; 2016 Rockwood 2604WS travel trailer
2014 Ram 1500 Laramie Eco Diesel; 2002 Harley Heritage Classic