Hey Jim,
We have not crossed paths in a long time. Good to hear from you. I should be at my hangar for the next few weekends because it is inspection time. Spent a chilly Saturday there this past weekend doing the easy stuff. Got my fingers crossed for warmer temps before I have to flop around on the hangar floor.
I mounted my oxy tank ("D" bottle I think) on the back of the electric flap actuator tower.
In my opinion, it was better structure than baggage sidewall and it was easy to execute the mounting. I did give up some ease of access but I combat that with up front flight planning so that all the connections are made on the ground. Its accessible in the air but not as easy as a sidewall mounted tank would be.