Gee wiz guys we used to put holes in the boat all the time to mount what ever needed to be mounted, tanks plates, drop through fins,water outlets, Dad's fishing boat had depth sounders, toilet port, you get the idea. Don't get too hung up on putting some well placed accurate well sealed holes in your boat. My tank brackets & intake, never leaked. My drop though fin did a little but that was due to the fact we designed it to be movable and our machine shop consisted of a band saw and a drill press. It never leaked enough to bother a thing while racing. In fact an old trick was to put some tide in the bilge before launching (not too much otherwise you'll look like Lawrence Welk's band) it kept the inside nice and clean.
