I had a 2009 GL1800 with Tow-Pac for 17,600 miles. Most of the time I was running a Darkside tire (Kumho run-flat). Biggest problem was getting the TP wheels aligned with the main wheel.
I found two pieces of angle iron, predrilled that were just right. Put bolts/washers/nuts just snug to hold the angle iron to the rear wheel. Used 2x6 blocks to hold them up. I was then able to measure from the center of the TP tire to the angle iron. Compared measurements from the front side to the backside and adjusted for a slight toe-in per
the instructions. See photos. Also Fender Lights I installed for Brake Lite/Running Lites/Turn Signals.