Here's what I did: I drilled out holes in both sides of the hull (actually for a fitting I got from West Marine) that 'just happened' to be the same ID as the OD of a piece of hose (clear, reinforced sorta like what is on the sprayer on your kitchen sink). The ID of the hose allowed me to put a dowel (put some lubricant on the dowel so you can easily pull it out later) thru it. The whole thing was 3 or 4 inches longer than needed.

I did my smallish end pour around the 'thingy' and when the epoxy was set up, I pulled out the dowel, grabbed the hose with a pair of pliers, gave it a good twist and it pulled right out. This left a nice smooth hole that I put the fitting over for decorative purposes (not really necesary), waterproof, strong, etc.

Someplace I have a picture of how I did it if you need clarification