I’m currently playing on Reddit Large which has this map seed: http://playrust.io/map/?Procedural%20Map_4000_478
As you can see, Outpost does not have a road going to it, and it is possible to wall it off. One of the nice changes with the Ring Road introduction is that generally it’s no longer possible to fully wall-off a monument. However, as seen in the linked map above, that’s not always the case. Please ensure all monuments have a road going right up to them to prevent them from being walled off.
Maybe it’s time Bandit has a road going to it as well, for the same reason.