[SURTEESS]

My 2 pennies worth for the day - here in New Zealand we do not spend money on salt for winter roads (thank goodness for our location, and global warming!!).

Before you put the plastic quarter guards on, what about painting a rubberized sealant under the wheel arch area. I have done this on a couple of cars (under the whole body).

Rather than using an automotive underbody compound (super expensive here in NZ) - I used a concrete stone block sealer, like builders would use behind a block wall/swimming pool area - buying a couple of 10L containers for around NZ$100.

It normally is only available in black, so I mix a small container of paint (about 50-100ml) in order to give it some OEM under body colour.

It will protect any metal area that has the possibility of water damage....also it is a great sound deadener for road noise, or if you live in an area where there are unsealed (loose gravel) roads.

It is also a great filler - so it may actually stop the gap where the plastic does not meet the metal (just apply 2 or more coats for a bigger gap issue).

If you do decide that certain nuts/bolts etc may need working on in the future, you can thin it down initially (take a sample out to thin down) with what ever brush cleaner is required & then apply to the areas first, before applying the thicker stuff close to the nuts/bolts (but not over them).