Dirk-
yeah, I put the tank right over the front half of the wing. with the engine set up of the ys pressure system I wanted to have two tubes easily accessible, so I ran them on the outside of the fuse in the tank compartment using "fourmost bulkhead fittings." They work great! The only problem I had was the compartment above the wing is pretty small to fit a good sized tank in there. So it was either cut up into the cockpit or find a tank that fit. I found some tanks that are flexible. You can heat them up with a blow dryer and mold them to fit.
I got a 10 oz. tank to fit perfectly. and I still have access to the pressure line on the engine.
Trevor