Once I have the shafts through the hole in the hull, I tape, or lightly tack the tubes in place.
I then use masking tape stuck tightly to the outside of the hull, and around the shaft to seal the holes. Then I pour epoxy into the holes and around the shaft form the inside of the hull.
Most of the mess is limited to the inside, and the epoxy reaches the tape on the outside, and cures to the shape of the hull.

Did that make sense?[&:]