Never pass up a chance to buy yourself a tool. Go get yourself a drill and a drill bit index. A good one.
Don't be intimidated with drilling holes in the new caps. Start with a smaller hole to verify alignment before stepping up to the full size bit.
Here's what I would do; I would test fit the pieces to my satisfaction, then take them off and have the body shop paint them for me. Then I would install them. I wouldn't leave it in primer. That's not a very durable finish. I would at least hit it with some rattle-can paint, if I couldn't afford the body shop route.
The gaping holes won't leak. They're not sealed by the plastic caps as it is.
Do it yourself. You can do it. The satisfaction derived is well worth it.
p.s. How can I get on your dad's birthday gift list?! I wanna pair, too!
