I purchased a second-hand 2016 3LT lined Carbon Fibre Top with Black Painted side rails.
I know Dereks is the same but with no painted rail, fully exposed and for a 2017.
I immediately had mine Xpel'd by my local application specialist that car dealers use in YYC.
These people have templates available to them for cutting the film, then show up and peel it
from the backing and then apply it. Mine is a mobile service & comes to my home.
One thing I found watching this application is that it most likely will involve a cut line between the
top surface at where it would curve over the side rail - in a valley (the point where the
painted portion meets the exposed carbon fiber on my panel (photos below).
This is because the film lifts or might get noticeable stretch marks if worked too hard.
The cut line can be felt but is not noticeable over time (as one just forgets about it).
View attachment 23030 circled the cut-line location in this one
View attachment 23031