Hi!
Why have the tank on the C of G in such a small glow model? It flies and hovers just as good with the tank just behind the firewall!
In my Yak-50 (gas) where I use a gas engine with walbro pump I don't have to think about where I put the tank, in that case the tank can be put on the C of G without any trouble. But in 99% of all glow engined powered models the tank could be mounted just behind the firewall without too much trouble.
Here is a second example on how an plane can be slightly modified to have the engine comply with the tank rule.
The Great planes You-Can-do.60 with the engine mounted on it's side instead of inverted.
...I'm still curious to see what the engine /tank installation looks like...Please!