Considering the intermediate precipitation here in Ohio, undercoating placed in the door and minimal amount of water that would actually get into the door I doubt it would be an issue. Rust prevention has also come a long way in the past fifty years....Rustbullet, POR15, undercoating ect.
Also, unless everyones truck is 100% original or restored, there should definately be some more participation piling up. Even if you just want a shameless plug of your build thread or photos, an upgrade of any form would be applicable here. =)
Wm
