Many years ago when I had a small pop-up camper I got an infestation of carpenter ants! The tell tale wasn't sawdust but tiny bits of styrafoam roof insulation. I saw some of the ants as well so I was pretty certain I new what I was dealing with. I used a product called Tero. I thiink it's basically a sweet syrup with borax. Just a drop on a small piece of cardboard left where the ants will find it and the problem was solved. Apparently the poison is slow acting so the ants keep bringing it back to the nest untill every ant gets poisoned. This cured my problem and the ants never returned over the next almost 20 years.