That is a good reference, thanks for posting it.
My main problem with glass lens surfaces is getting caught in the rain and having everything thoroughly soaked through and through.
As soon as I get home, I take my wife's hair dryer and heat up the receiver and magazine holder to get it all warmed up and started drying out. During the winter I set the rifle up against the wall a couple feet away from the wood stove to heat it up.
After it is warmed up and the water evaporates, I spray down the entire rifle inside and out with WD-40.
The main problem I experience, and the reason for the WD-40, is not rust on the barrel or receiver surfaces, but all of the screws that attach the optics to their mounts rust. Kinda like the only things that rust on my handguns are the hand grip screws. The WD-40 prevents that but often I accidentally get some of the Wd-40 onto the lens surfaces of the optics.
Since I work in a laboratory, I have access to pure unadulterated 200 proof Ethyl Alcohol, and that is what I use to remove the WD-40 residue on a cotton Cue-Tip. It cleans up the WD-40 oils and leaves no residue at all.