Easier to make a number plate (and maybe make an error) than to try to do this to the existing bulkhead/hull.

The area I plan to attach it is inside a hanging locker, at the back of the locker is the hull.

Larry gave me a cheap easy out... stick on numbers epoxied over... that would work, but I wanted something a bit classier. Every documented boat I have ever seen has had the numbers routed into a chunk of wood and that wood was glassed to the hull.

I have a router, but I usually use a guide when I am routing an edge... I might try to route this freehand in some scrap first.