Ran into the same mess on a silver Tacoma bed last fall, tape lifted the sealer right at the body line after a day in the sun. What worked for me was 8 to 10 seconds with the heat gun set low, maybe 200 degrees, and I keep the nozzle moving so I don't cook the paint. Then I press the edge down with a plastic squeegee while it's still warm and let it sit a minute before I spray. Pull it at a slow 45 degree angle and the edge comes off clean almost every time. Cheap tape still fights you though, so I quit buying the no name stuff.

Man, I feel this in my soul. I once drowned a cactus, which I'm pretty sure takes a special kind of talent since those things basically live on neglect. My roommate told me to stop watering it every other day and I acted like she was trying to sabotage me. Three dead cacti later, turns out she knew what she was talking about. The finger test changed my whole plant game too, and now I've got a pothos that's survived almost a year, which is basically a world record for me.