I use Cool Power 15% and while I don't advocate this, here's what I do:

After the last flight of the day I drain the tank (With a fuel pump), then I put the airplane back in my car... Sometimes I wipe the oil off it if it has a 2-stroke.

Then I go home.

I run the engine again the next time I go to fly it.

Like I said, I'm not going to say everyone should do this, but I never do anything special, and all of my engines run great with no rust.