I would do the following to prevent cracking and splaying of the wrap.

Put the blue or green painters tape on the area to be drilled inside and outside of the shell.

I would build a fixture of wood that can be clamped to the shell that fits snug against the shell. A 1" wide by 1/2" thick piece of wood would work best for both sides. Clamp that on with 2 pressure clamps and then drill your holes. I have used this method on multiple re-wraps and drilling other holes on shells. Works like a champ.

Michael

Very good advice from CTMichael V!

As a second way of doing this, I find that for drilling "clean" holes in drums, the use of a spade bit works well. (See attached picture).

If you can drill from the inside of the drum, the sharp point of the spade bit will poke out first and be visible before you drill all the way through. Once it pokes through, stop. Then, drill from the outside in and line up the sharp point on the spade bit with the hole that it already made when you drilled from the inside.

This really helps the wood from splintering at the the hole, especially on softer woods.