I have been in your shoes. I had a 1985 Grand Am that I was chasing the water leak for at least a year the fron floor board was wet after a rain. So last ditch effort I jumped in the trunk with a flashlight and had my brother hose her down, turns out the water was coming through the studs on the rear tail lights mount. It would leak into my trunk go under the carpet miss the spare tire well run down the rear floor and settle in the front passenger floor board. I doubt that is the exact same problem but any hole that goes through the body is a point it could leak. I suggest taking off as many interior trim panels grab a flashlight and a water hose and see if any turns up.
Bronco Nation 1100. Everglades, Desert Sand
Res: 7/30/20 ordered 1/22/21 reorder 10/15/21 changed to Everglades 3/9/22 schedule 8/29/22 bumped to 9/5; 9/7/22 blend, 9/9 Mods, 9/26/22 completed, 10/7 shipped, 11/3/22 delivery