I think I'd get the set-up as pictured and the double male fitting as you mentioned. It'd be more versatile that way. JMOEd
I copied a picture of what I intend the final fill station to look like for my scba tank. For now I'm thinking of a male Foster fitting on the end for refilling purposes. But after thinking about it for a while, I might go with the picture then use a double ended male Foster fitting. That way I just take the male to male fitting off to connect the hose to fill the AG. We'll see when the parts arrive. I'm headed to the hydro shop tomorrow to get the scba tank tested and filled. Hope it works OK. Never done this before. Dave