I think I get what you are saying. In a lot of unpleasant events you may feel the need to be better armed then normal but there is still some law and order in effect and openly carrying a gun may get a serious response. You would probably be best off carrying a handgun and keeping a long gun concealed nearby in your home or in your vehicle. I'm thinking like after a major disaster where there is a breakdown in law and order but not a complete breakdown and it is expected to return.
For a higher threat scenario you might look to security contractor types in Iraq and Afghanistan for ideas. Use shorter weapons if possible and try to conceal any armor or gear by wearing a large shirt or jacket. I remember seeing something on TV where one PMC had their guys wearing photographer type vests to carry spare mags and conceal their body armor. That's not going to fool anyone up close but from a distance if you concealed the rifle as well you might seem unarmed at a glance.
I think stuff like tinted windows on your vehicle, short barreled guns, and folding stocks would go a long way in enabling someone to move around without drawing attention but still able to respond to a serious threat. Think twice about violating any laws though, I wouldn't want to get locked up when things are going to pieces.