I don't know why people are so keen on drilling holes in their air tanks, especially with more reliable options available. It's probably because that method is the only one known, but it should be known that it's not a good idea and there are definitely other options worth consideration.
Do consider that many know of the air coupler option. It would be better to tell us exactly where to find these elusive little things, rather than tell us that we don't know they exist. I've known that there are "better" ways of attaching a schrader valve since the G2 Douchenator was comissioned, but where are they? I've wasted enough of my time [and that of store employees on wild goose chases] for a part that virtually no one has heard of. Drilling a hole and screwing in the valve has so far been an easy 5 minute operation that holds over 120 PSI without leaking.