Is this plan (for two people) feasible:
Rebel--glad to see that you are interested in coming to Moab!
I think this is the type of meetup at which you can spend whatever amount of time you like. We actually had someone swing by for just a couple hours or so a few years back! (She was actually moving from NM to UT!)
Having said that, you'd get more out of the experience if you could stay longer. I think there will be a lot of mustachians to meet and chat with, and there are a lot of fun things to do in the Moab area.
If you want to stay where the majority of the attendees will be, that would be in the campground. The campground does fill up, so if you are thinking about staying there, I would grab a spot as soon as you can. They do have a generous cancellation policy. A link to the campground's website is in the second post of this thread.
Hope that answers most of your questions!