Due to no positive RSVPs, my 4E game will not run this evening. We'll try again next week.
In the meantime, I've run across the Western Marches as a campaign style and I am very intrigued by it. It is very similar to what I was envisioning, but even more so. I going to give some thought to making that the implicit definition of the game, with the exception of game scheduling. My schedule as DM is limited, but I can set a specified time and run for whoever shows up. While I can do it, I can see 4E combat being time critical to making this work.
This bears some serious thinking about.