Two things:
1) When that plastic piece beneath the rear of the headlamp housing breaks, more can be ordered here
https://www.amazon.com/gp/product/B00FZM5BPW/ref=oh_aui_detailpage_o09_s00?ie=UTF8&psc=1. (as for the price
)
2) This is what is beneath the front headlamp.
(I cleaned-up the area before taking the photo.)
https://1drv.ms/u/s!AhsZJDCN8kMMgaQU-vZDdLWI65-pGg
Water and road salt get beneath the headlamp,
and sit.
So there is already a fair amount of rust underneath and next to that white plastic headlamp clamp-down piece.
I greased it down with a heavy bearing grease, to help reduce corrosion.
That's not the worst part though. See the wire harness behind it? Imagine having salt-water sitting in each of those holes.
Bearing grease would probably break down the seals and plastics. Silicon is safe to use but won't really stick around.
The only thing I did there was shield the front/top part of it using a rubber glove. Covering it in a way that will trap humidity, water, will do more harm than good.
Slathering a ton of dielectric grease should help.