How about just making sure the frame is dry and keeping it properly closed up? See
http://yarchive.net/bike/frame_rust.html for Jobst Brandt's explanation.
Short version: A properly made frame has no holes of note - except for the top of the seat tube. This should have enough grease to stop water from getting inside. At this point, there is no water to cause rust, so there can be no rusting on the inside of the frame. The head tube may be in danger from sweat, but that is summer, not winter.
As for rust on the outside of the frame, I would be inclined to make sure to keep up with the touch-up paint if you scratch your frame.
Tor