@Rooks
possible, but that won't help him smuggle gear with him. You'd need weapon mods to get RP on your weapons too.
character wearing an outfit with active optical
camouflage and carrying a weapon larger than Heavy
Pistol size needs this modification to receive the bonus
of the camouflage
Course you could always get a concealed pocket and chameleon coating under a lined coat with RP for -6 (or more?) 
Concealed pockets won't fit a sword or shotgun, they do list examples of what would fit.
As for using multiple armors, you only keep the benefits of the best for armor unless they are stacking (have a + sign with their armor value). I recommend that if you are going to wear multiple armors, they should be designed to stack or be concealable. Example: Armor vests are made to be worn under the clothes without any real bulk. No reason you couldn't wear one and a lined coat or perhaps even an armor jacket. Useful for if you get to the front door and they have a coat check, "May I take you jacket, sir?"
I'd suggest you think about the goal of your character. Concealment is for fitting in. You aren't making yourself invisible, but making your illicit goods fade out of sight. A full camel eon suit or RP cloak is meant for you to be entirely unseen. Having to hide your weapon implies that they have seen you, which means you've failed.