Good luck....
The boat maintenance people in my area use a heavy duty spray they purchase at a big box store. There is a flexible sprayer attachment to penetrate holes and corners. They report good results, but note it can take several applications in a season to eliminate the pests fully. When I sold my last boat, I went through a commercial termite eradicator, but the experience was awful. Part of it was trust in that I thought they were continually upselling me because it was a small job. I finally caved in and just let them do it although they did give a pretty good price break ultimately. Good luck. RD