I will lay you odds that it is the turn signal stalk.

If the tail lights and instrument light light at all it is not the fuse. Due to the fact they work in one position of the switch but not in the other position pretty much clenches it being the switch. I went thru almost identical issue except both sides of my tail lights went dead with headlights on as well as all the dash lights.

To further justify that it ain't a fuse, the power source (fuse) does not change when you turn the headlights on or off, so if they worked in one instance and not the other, what else is common to the circuit?

 

Should be able to verify stalk switch by reading for plus volts to ground at fuses F8 and F2, switch is upstream from them.

 

I ripped off a corner marker light while off roading, which in turn shorted against the frame (or bumper, I can't remember which), and killed my passenger side running lights and instrument cluster.

It's going to be one of the fuses under the dash.

 

By the wiring diagram on section H4 page 1, the fuse F8 gets power from the switch, then drives the right side tail light, right rear marker light, and front side light. So if any of those lights is on, it is neither switch or the fuse. If all are out, could be fuse, could be switch.