68 Barracuda FB glass pinchweld modification idea.

Instead of installing drain tubes, could a "rust-proof" finish to the metal underneath be more feasible? I ran into the same rust problem in the lower back window channel with my '68 GTX. I "repaired" it in 1981, but the rust is re-emerging, so after the Cuda is done, I will be tackling the GTX again. This time, however, after metal work is done, I want to find some type of finish impervious to rust, such as OS-PHO, to pre-treat the metal before painting. Man, sometimes I wish these things were made of stainless (just kidding).