Try Comet cleanser. We pulled into campground late one evening and as soon as we got out of the truckthe neighbor showed up with Comet, and said the ants were hell, and he'd get the comet down. He put it around the tires, hose, power cord, everything that touched the ground. Apparently they won't cross it.
There were ants everywhere at that campground, but none came I the camper. Every camper had the comet around it. The grocery store down the road had cases of it, and I hadn't seen Comet in years.