Damn, that sucks about the tape, sorry about that. I wonder if those who did it before me are having the same problems.
To be fair to Monstaliner, I think the stain you're seeing is the 3M rubberized fender spray that the body shop used and not Monstaliner. The small spot of rust that was...
The tape job on mine isn't perfect, but unless you're looking really closely it's hard to see with black. I just used 3M masking tape and took my time. If you want to be really exact, start with really narrow tape to get the line right and then wider tape over the back edge of the narrow tape...
So while I rolled my truck myself, I dropped my bumper off to be sprayed. The shop didn't want to screw up their spray gun so they rolled it on with normal roller, doing an absolutely terrible job. There's zero texture to the monstaliner and if you breathe on it, it scrapes off.
So now I have...
While the prep was a huge pain in the ass, I'm definitely happy with it.
The aluminum tape to cover the holes worked pretty well but not great. You can definitely see the outline for some of the holes, but most people won't notice.
1 gallon was exactly the amount I needed for the sides and...