Anyone have proven/time-tested tips/tricks for maintaining firearms during extended use in wet climates/environments?

Good gouge. Down here in the sunny, sultry South... anything that finds itself outside after sundown in the summer is going to be soaked by morning. I generally coat all internal parts with a thin layer of WD-40 (after cleaning), and it seems to work well (no "explosions" and or "gumming up" as some warn).

LCDR Joshua Gillespie - WD is good stuff, fish oil derivative with many uses. A small can is a must for go bag. Duct tape and/or 100 mph cord (550). Good ap knife, meds, comm, weps, compass, a few d rings.

I've used a lot of expensive lubes, and have found that CLP and WD are as good or better than the "fancy" stuff. I keep rolls of "Gorilla" tape (basically a more readily available variant of high-end duct tape) and electrical tape in stock... because I use the heck out of 'em. I use "Ranger Bands" for many applications... from securing pull tabs on packs and webbing, to affixing things I don't want to "fall off". I don't smoke, but I carry a lighter everywhere I go, and keep several in a waterproof bag along with ferro rod. For my kayaking trips, I took an old Cordura plate carrier and replaced the ballistic plates with closed cell foam inserts to act as a MOLLE life jacket. This allows me to keep an IFAK, fire-starting materials, knife, and other "last ditch" essentials on my person in the event I get rolled, and loose any of my other gear in whitewater.