Chu Lai 68-69 Seabees, not in a battalion but base maintenance, our guys filled in for the Marines at time as door gunners, in perimeter bunkers, some local patrols, hauling ammo/bombs and clearing mines with our dozers.
I think the uniform thing was local, in CA they suggested that we didn't wear our uniforms out in the public. Flying into New Orleans I had to wear my uniform, I took the bus to Shreveport and never got a word said to me, in Shreveport I didn't have a credit card so couldn't rent a car. I went to the local car dealer to try and buy a cheap car and have them buy it back when I left. The dealer rented me a car for $10/day and $.10/mile I expected it to be a junker when I came back into the office to tell them I couldn't find it he took me out and lead me to a brand new(10 miles on it) convertible and said "Have a good time, you deserve it. Bring it back in one piece please".