Our bike has 7 braze-ons for cages and the center one has a doubler. The only one the stoker finds convenient is the same as yours. My guess is that your top tube is close to the the top of the bottle, so if you had a cage that would allow a more angled extraction, it would be easier for the stoker.
Somewhere in the UP. There were other types of "bikers", we were all Bro's.