100S Potential Rust Pockets

I havent given the truck a good wash for a while so I spent Saturday afternoon with the high pressure cleaner, detergent, wax, polish and WD40 etc
Although I have had the vehicle since 2001, I have just found two potential rust areas that were FULL of red dust and sand
The first was in the roof channels where the roof rack can be bolted. I removed the plastic caps (3 on each side) and ran the pressure cleaner into the channel. Could not believe the amount of sand and mud that came out - I had to run the pressure cleaner for about 10 mins on each side before I got clean water flowing freely.
The other more serious spot was in the left hand rear wheel arch - just below the fuel cap. There is a plastic guard that bolts onto the rear of the bumper where it wraps around under the fuel cap (It is there to protct the fuel lines from the filler cap to the tank) I removed the plastic moulding and behind it there was at least 2 cups of dirt and sand

Has anyone else found any dust/dirt collection point on a 100S