I don't run traps, and I drain the tanks regularly. After driving semis for years I'm surprised how little water there is.
I've heard the same thing about valves if you're gonna drive it in the cold. I don't do that often, so it's never been a problem for me.
I run the two tanks in line. Compressors feed both, valves tank pressure gauge, and horn are fed direct from the tanks. I also have an emergency feed line to the tanks from a Schrader valve in the bumper in case of compressor failure.
I got a couple of Suzi's. See my signature for the details.
They're not comfortable, but not as bad as some. I'd like a big wheel bagger at some point in the next couple of years, either HD or metric.