OK, I took another look, and removed the one screw holding on the reversing switch, which gives a much better view of that wire and space. There's far more room than I thought, a good 1/8th inch? I'm confident I can get some insulation in there or slip some stripped insulation or heat shrink tubing over the wire (or both - belt/suspenders) w/o problem.
Any thoughts on a front truck/wheel replacement, or the near-short between the pickup and the truck/screws?