Pretty much any asteroid or KBO would be good for habitats, though I guess out there one problem would be that it would take a long time to resupply the habitat.
True. I wonder how much of the colonist's needs could be synthesized locally from available raw materials?
I suppose that the remote location might be attractive to people who want to avoid attention, so I presume that they wouldn't want to be too dependent upon external supplies.
The option of habitats on dwarf planets near the edge of a solar system has some possibilities for more traditional SF games too - if there are this many KBOs in a typical star system, they might provide an interesting location for a pirate base or a secret research installation.