@SchmidtFG Some of the Mighty Griffin parts are included in the main template (e.g. the paintable Front Mask), and some have their own separate templates (all of the parts in the Accessories folder are Mighty Griffin parts). As for the stoneguards, none of the MG stoneguards are paintable as they're all chrome, so they don't have templates. If you have a paintable Thor stoneguard, it might be added by a mod.
And you're correct about the sun visor, it doesn't have a proper UV map. To paint the sun visor (and main mirrors) on the R 2009, you need to paint the bottom left corner of the template. For example if your texture
looks like this, the truck will
look like this. There's no way to put a detailed design/logo/text on them, you can only make them a solid colour. This is because of the way SCS created the trucks, and there's no way to change it on a paint job, aside from using a mod that adds additional mirrors/sun visors. Some of the older models are lower quality, and since the R 2009 has been in the game since it launched, it unfortunately has this issue. You'll have to work around it by making a paint job with solid-coloured sun visors and mirrors.
Hope this helps!