Because power does not flow through the switch in the stock fog light set-up. The dash switch activates the relay and power flows through the relay to the fog lights. Here is the OEM fog light harness, it plugs into the 10 pin connector by the air box and replaces the non-fog light headlight harness.
He still makes them: https://www.ebay.com/itm/Jeep-Comanche-MJ-Truck-Headliner-Panel-Custom-Made-in-the-USA/402113132131?hash=item5d9fcf7663:g:RVQAAOSwxxdZa50G
You have a BA 10/5 if it hasn't been swapped out. Look for two plugs with square drive centers, those are them. Fill to the bottom of the upper plug. This was just recently answered (in more detail) but I can't find the thread. Good luck.
EDIT: found the thread, at the end.
I for one am glad you are keeping it. After all that hard work you should enjoy it for a while. for front flaps:
https://www.ebay.com/itm/NOS-OEM-Jeep-Cherokee-Front-Splash-Mud-Guards/264694052668?hash=item3da0feb73c:g:IAkAAOSwcLlejjiZ
Boostwerks Engineering makes one for the 242, contact them for your specific application. They've been very helpful in the past.
Welcome, post in the registry and start a build thread with lots of pictures!
Looks great, you're one PATIENT man!
I drilled out the plastic torx heads, put in stainless torx bolts of a similar size and painted the centers black, I know it's not OEM, but I never have to worry about the silver rubbing off. Just a thought.