I followed all your recommendations (clear lacquer and Fluid Film).If you have a chance could you please post a picture of your chosen drilling location in the bumper. I may do this as well.
I choose my mounting location for a few different reasons. (1) It's a flat area for good mounting (no bumper curvature). (2) It can be hidden by the OE license plate bracket, or maybe a flip-up license plate could be adapted. (3) The location is centralized in the event I choose to plug-in an onboard charger/maintainer/desulfator, or something else.