Quick update.
After the paint had fully cured I gave it a couple of coats of filter to tone down and blend in the camo a bit, then varnished/decaled/varnished, so at that point it looked like this.
The I went at it with a starship filth wash. Hmmmmm, dirty.
After 24 hours most of this was taken off with a brush and cotton buds & odourless thinners, which left it looking like this.
Although that all looks quite dark and dirty, it's eventually going to have a pigment scrub which will lighten it and hopefully leave it looking like dry dust over ingrained dirt. I still have to clean up the top of the hull, so no pic of that yet.