"The
engine definitely needs an external purge button."
I agree. In the mean time you shouldn't need to purge the
engine unless it's been sitting unused for a long time. The trick I've found on the long hose is to disconnect it from the engine when you need to, but don't disconnect it from the tank. Then turn the tank off. The hose should stay full of
propane a long time that way.
If you disconnect it from the tank the
propane comes out and air gets in.