Hey guys, just wondering if anyone has a GUIII Wagon and has fit an air tank on it,where was it fitted?

I have been reading up on old articles and there's one with a 9L tank mounted behind the trim of the LHR quarter, sitting on top of the wheel arch, however I bought a 9L tank today and mocked up the fit, but the trim wont sit flush if the tank is there and the tank itself wont fit as the legs put it out a few mm.

Is there anywhere people could suggest it get fitted which keeps it both hidden and safe from blunt force?

Cheers.