Its just not that critical! Put the 14oz tank in there and go fly.

John,

If it were that critical your "pony tank" setups that you have most graciously shown us wouldn't work and you have most likely doubled the fuel capacity in the pictures shown.

In the extreme setup it maybe a problem, but just how much positive pressure do you need? Most of these engines can be setup then tuned to run without positive tank pressure anyway. We ran without pressure or with pressure for years flying U-Control not a big deal.