I'd black out the c clamp. I'd worry about how well that translucent paint would hold up over years of sun exposure.
I would think it would hold up just fine due to the headlight lens usually having some type of UV protection.
From my experience so far. I have not seen any negative effects from my side markers I have tinted. It has been a little over a year I believe and the truck is always outside.
If it were to be applied to the outside of a taillight or something, then maybe after awhile it could be effected die to the exposure. I will need to research it some more.