I have Snowy Escape installed, just haven't lived there yet. It is/was a bug that may have came with Island Living (it happened all the time when my sim lived there). I hadn't noticed it lately though.
I just have my sim live in Newcrest and when the bug was active back then, I just removed the front door and put up a door frame (like you use for hallways). No sim came in or stepped on the property. They would stand on the sidewalk and eventually walk away if you didn't go there to talk to them :D No hit on relationships either. I play a single sims, so in order for the door frame to work, I had to replace all doors with door frames in the house or they would walk in and knock on the bathroom door :D
ETA: The door frames didn't affect the weather in seasons either, as long as there was a roof over their head and walls. Don't know if that changed though, haven't played that way in a while.