Backup cam cable run

97' 3 door. (red)

I'm installing a wired backup cam.
https://smile.amazon.com/gp/product/...?ie=UTF8&psc=1

It came with 2 cables for the rear camera - cable A) just right "IF" I can follow the frame to the cab, enter the back of the cab, up to the headliner, across to front center and 2" down to mirror(screen). or cable B) follow the frame up to the headlights, make a coil, back to the firewall and through, up the windshield molding, over to front center and the mirror. I'd really like to do option A but I'm having a problem figuring out how to get through the back of the cab. A flashlight shows what looks like a cable box on the back of the cab - and to get to it I'd only have to remove the bed. There is a 2" removable plug, outside, at the back ds of the cab but I can't tell where it goes. And is the cab double walled. Can I pop off the corner molding, from rear armrest <-> headliner? and how?

Thanks

Problem solved. Back corner of the DS about even with the back armrest on the outside is a pop in plug. So cable A, along the frame, over the filler tube, up between the bed and cab to the hole (I'll mod it to allow it to be put back in) the fished a string up to the upper back DS corner - after I removed the plastic panel around the back vent window, seat belt hw - only thing left is to fish over headliner to front center.

PS - so I took the 12v->5v adapter apart, removed about 8' of wire, removed the spring and side clips and soldered some 6" wires in place. The dome light has 12v & gnd so that's where the 6" wire goes. I wrapped the adapter in duct tape and stuffed it in a grouve above the head liner and put the dome light back.