Originally there were no door jamb switches. NAPA sells a universal door jamb switch, that works well. I just cross wired the switch to come on when a door opens, or I have a switch on the new console that turns it on. You are correct on the ground.
The radio delete modification you made is very interesting. I went to a trophy shop and had them make a size specific plate for the radio delete. I had the plate done in brushed aluminum and scripted with "Advance Design"