If it is a minimal effort to dull it slightly, then it would be best to do it before the side rails etc are mounted.

It would be easier to do now for sure.

Maybe a light coat of satin clear to take the edge off if it's not too much trouble?

Definately not too much trouble, I thought I'd see how the clear came out off the gun as Anthony said they don't really have a satin for that particular clear (as it is for automotive applications) but he could add matte properties to it if I needed.  He said to see how it comes out first without polishing as usually it is slightly dull until buffed up.  Maybe it came out so glossy because I thinned it out 3 parts thinners to 1 part clear for the finishing coats as for spraying cars.

Might pop down there today to get a little mixed up with the matte in it, see how it comes out.