Questions on the liquid mask, please. Did you spray it on (as suggested by the manufacturer) or brush it on? What tool did you score it with to remove the squares? Looks like you removed the unwanted squares in the pic in post #1294.
I bought some liquid mask about two years ago and tried it on a test set-up I made with plastic window material. My first concern was how to remove the mask after I paint. What I ended-up doing was making folded-over tabs out of 3M Safe-Realease painters masking tape. I placed a couple of the tabs on the window surface and then sprayed-on the liquid mask. After painting, I was able to pull the tabs away from the window and worked the liquid mask off from the inside of the window area outward instead of the other way around. This way I did not have to pick at the outside edges of the painted area and risk chipping the paint. Worked well. Just another approach.
Can't wait to see your results with the cowl.