backup light switch.

There are lots of ways to go about that, depending on "how good" a parts guy you have. One switch that comes to mind is the old Mopar clutch switch, although I don't remember it may work the wrong way...in other words it may be normally closed (when at rest) and you'd need "normally open." In the world there are literally thousands of various types of spring return switches, Microswitch is a brand name that make many. You could build a bracket that allows a switch to be activated off the linkage there on the engine bay side of the firewall.

Ever screwed with magnetic reed switches? Fasten a magnet to the linkage, built a bracket for a reed switch

Another approach you might use---you sure at this car's age that "inspection" might not have a few exceptions for old cars? After all you cannot exactly get parts at the dealer.............

Last it is just not that difficult to remove the column from the vehicle. Maybe you can rework "what's there"