They aren't hard to get off at all. When the car is in the air, you can look up into the rear bumper and see the 8 nuts that connect to the bumperette studs. The biggest issue with doing this is the space between the muffler and the rear valance. I ended up just removing my rear valance and that gave me plenty of room. In all honesty, I could have removed the bumperettes using extensions on my sockets, but wiring the license plate lights required the extra room.

So, the steps I followed:
1. Under car, remove rear valance.
2. Behind car, remove license plate lights from bumperettes.
3. Under car, pull license plate light wires into the rear bumper.
4. Under car, unbolt bumperettes from inside rear bumper.
5. Behind car, pull bumperettes off (may require light tapping on studs in bumper).
6. Behind car, drill holes in bumper for Lite n' Bolts.
7. Under car, wire and mount Lite n' Bolts.
8. Behind car, pop caps into the holes left behind by bumperettes.
9. Under car, reinstall rear valance.
10. After about a month, the rubber impact strips loosened and sat straight back. As a result, I got some epoxy and stuck them back on, they've been there for 1.5 years without coming back off.

Eventually I plan to get rid of the Lite n' Bolts. I'd like to get license plate light holders from a BMW 2002 (our host sells them) and mount them onto the bumper. The Lite n' Bolts illuminate the license plate fine, but they are blue LED's and it just doesn't look right on a vintage car.

Looks great! One question did you mod or remove the valance panel?

I'm not sure if the question is directed to me or Will. On my car, there is currently no rear valance. I'm thinking of getting a fiberglass one, but need to see how much space there is between the top of the pipes and the bottom of the bumper. It didn't look like much. If I got one, the cut around the pipes would leave the valance pretty thin.

If it's a question for me, I removed the valance so that I had access to the license plate wiring and rear bumperettes mounting studs/nuts. I reinstalled it when I was done. If I had a GT3 style muffler like mclmk8d (some day I will, fingers crossed) I would modify a fiberglass one.