Your problem seems to be that you are shorting the orange power wire in the fuse panel to ground through the dome light or the tail lights when you turn on the headlight switch. It is more likely that it is the tail lights or the front parking lights. One of those or the wires that feed them is probably shorted to ground.
below are three diagrams to show that this is possible.
This is the headlight switch and you can see the orange wire and the brown tail light wires. They make a connection when the switch is turned on.
This is the switch itself showing the brown wires and the orange wire.
This is the fuse panel showing the orange wire in the panel (bottom center) and if you follow it to the brake light switch and the headlight switch, you can see the connection between them and why a short in the parking light wires would cause the fuse to blow.
The orange wire also feeds the dome light, but if it was shorted then the fuse would blow anytime you opened the door or turned on the dome with the headlight switch.
What I am reading is that you only blow the fuse when the headlight switch is turned on.
Take your multimeter and check the tail light wires for continuity to ground with the headlight switch off. When you get very low resistance near zero on one of the lights then that is the grounded wire.
Most likely it will be one of the rear wires that run along the frame or at the rear of the truck where it has been rubbing the frame. If you can find the connector for the rear light wiring and disconnect it and you no longer blow fuses you know that the rear lights are where the short is located.