Not sure why you disassembled to apply the Plastidip. Just put some painter's tape on the paint about an inch from the chrome grille and spray. Spray right on the paint! Then spray several coats. Once dry, peel the plastidip to the edge of the chrome. It will "tear" along the sharp edge of the chrome piece.
I did this recently on my white Touareg.
I used 2 cans of black Plastidip and part of a can of "Glossifier" to make it slightly shiny. It's held up for a couple of years.
Just did this to my chrome grill. It had some bad scratches and looks like the previous owner had it repainted chrome. Got a little bit of orange peel texture as it was my first effort at plasti dip. Does it look ok or should I try and fix the texture?