devb22
+1y
From my experience I would put them somewhere where they are somewhat out of the elements. I know that is almost impossible, but you don't want a massive amount of condensation and dirt getting into them...
I have my valves in the bed on the front of the bed where it meets the cab. They are mounted there with brackets and I made a removable sheet metal cover for them...its clean and you could never tell!
I haven't had any problems and they are covered, but when I need to get to them its 4 chrome allen heads and pow!
Hope this helps!
Dev