Amazing update... Finally had the chance to go check on the camper (it's been raining for days here!) and, first plug into truck (after monkeying with the 7 pin connector last week), truck was completely happy! I hooked up and drove a bit and used brake controller - brakes on the trailer bit as they should. I am so relieved! The fact that RAM brake controllers have been recalled on years around mine and since the camper sat for a bit and since the previous owner didn't know much about it was the perfect storm for me to assume (yes, yes, I know, bad!) the worst and check all I could. What I've learned:
1. Sometimes the easiest solution is not the most obvious.
2. You guys are a wealth of knowledge and I'm thankful for you.
3. If a trailer has grounding issues, chances are position/brake/turn signals won't work so no need to chase that.
4. Truck will stop all 15,000 lbs if I ever lose brakes on trailer.
5. Wiring diagrams shared can come in handy, so thank you for sharing them!
Much appreciated again. I very much appreciate each and every answer and possible solution!