Honestly I tried to do the same thing, find somewhere far away from other civilized places (which isn't that hard since most are on the right / right bottom side of the map) where I could make it seem as roll play friendly as possible that some one would try and settle. I ended up finding that place, a bastion in the wastes if you will, somewhere that has electricity, somewhere that has a view of the surrounding landscape, somewhere that has 'some' room to build and most of all, somewhere that is fairly easy to defend from the get go... That somewhere is WKML Broadcast Station. It has a nice solid main structure, with 3 (working) generators (for RP purposes), 3 broadcasting towers to build from, one point of entry (the stairs at the front), the ability to place turrets / guard points all around the ledges of the area... I tried to make it like a castle if you will, myself and the more important things at the top where it is easily defensible and the common things, ie Housing and such on the car park/ roadway just down from the stairs and even then down there it's not hard to defend / wall off, you've only got to make a small wall on the left side (standing and looking from the roadway in front of the area) to block off that way up, a little larger walling on the right side to block that, the only real fencing / barricading needed is along the front in front of the roadway. The downside is it's so close to the Deathclaw Sanctuary (they tend to spawn in and around the area at high levels). There's the bloody sniper 'Drifter' on the other side (who also attacks ANYTHING, Bonus to defense of the place I guess). Also there is a Random Encounter 'Type A' located right up in front of the WKML Broadcasting station (Trigger is running up the stairs). I have only built up the top so far, once I have no space left then I shall move down to the next level and continue building dwellings I guess. Hope this place helps someone looking for somewhere more challenging to build a settlement, you can also go to war with the Talon Company mercenaries at Fort Bannister for equipment caps, Role Play etc.
