[HoMiPa]

I removed the crown molding on the front shell of my TM back in 2017 when I did the remodel (so I could paint without taping off all the molding, I put the molding back on), and there were definitely wires running through that on both sides, and in the middle under the flat molding running down the center. So I'm sure the wires to those rear running lights run behind the crown molding on the back shell.

I can't answer any of your other questions. But the crown molding pops off easily, so at least there's that. :-)