On the base :
how\'s about something like martian soil, a nive red-hued desert, with a couple of nice rocks strewn around, and a big rock on the side of the base, something to make camp against, maybe even a \"natural\" outcrop, to build a campfire under.
on the scout :
how\'s about painting the armor plates in a chapter color, and the cloth of his breeches in a camo pattern that matches the base.
you might even pick a nice contrasting color in relation to the base (eg. ultra marines on a martian base) and have the armor plates and other chapter color stuff strewn around the camp...