Here’s my take:
Though it can be frustrating, I don’t think the guy with the permanent was in the wrong. It might be a spot he fishes frequently, or he looked at a map like you, and just planned to fish it. He might have even been waiting for you to leave rather than jumping in right next to you and setting up while you were there. Nobody really knows for sure.
The way I approach permanent shacks is I will drill holes fairly close to them if nobody is fishing in them at the time. They can’t lock the space up to themselves just because they are parked on it. If somebody is in the shack, I’ll give them the space I would give anybody else.
Sometimes it stinks to have a spot or area in mind, only to get close and see a bunch of perms scattered about, but it’s not a lot different than with boats in the summer.
I try to respect everyone’s personal fishing bubble as much as I can. Luckily I live in an area where that’s pretty easy to do – usually not a lot of pressure on my lakes.
Tucker