I also plastidipped my side chrome trim (and front grille). It has lived through 2.5 years of -40°C to +35°C climate, road salt and pressure washing, and still looks good. I do have one corner that is starting to peel though. It's hard to stick to that shiny chrome.
As far as taping goes, you don't tape to protect the paint, you tape to provide something to pull up the plastidip from the paint to the edge of the trim. The plastidip will "rip" along the edge of the trim. I leave about an inch spacing between what I'm plastidipping and the tape. Then spray right on the paint. Any overspray rubs off with a finger tip.
Tons of videos online showing the best way to dip.