It's rather common in some other countries (where Nitromethane is either extremely expensive, or illegal ) to run a "Glow" engine on low or NO Nitro. These engines typically have a higher compression ratio...

You could modify your engine(s ) to increase the compression ratio...then run them on just Methanol and oil.
Have a look in the Glow Engines forum...it's mostly Aircraft engines, but the principles are the same...