I definitely think the idea of a personal hideout is a cool idea.
I don't think that it should have any tactical advantages, though. Purely cosmetic.
My two ideas for personal hideouts for our pirates.
Idea 1.) This one is personally my favorite. Who doesn't like a secret hideout/base? Player hideout vaults are the answer.
It would use a similar system to how gold hoarder vaults work. The player would purchase a key from the gold hoarders for an absorbent amount of gold, and the player would then take that key to a vault of their choosing, and place it on the pedestal to claim an instanced version of that vault (would not effect normal vaults). Once your hideout is opened up, the room inside is noticeably larger than normal vaults, and there would be space to place furniture, decorations, etc from your adventures. Commendations could be tied to decorations as well, so for instance if you're a legendary sea dog, you could get a golden wall plaque that shows your arena stats. A feature I thought that would be kind of cool is if there was a separate room inside the hideout where your accumulated riches would sit, and could change in real time as you get more gold. This could be shown by piles of gold, chests, trinkets, skulls, etc. Obviously these are purely decorative, and just act as a visual representation of your earnings. There could even be an informational tablet or something that tells you how much gold you've earned overall.
Idea 2.) The upstairs portion of the taverns have finally been finished, and players can rent their own rooms. Similarly to player vaults, these would be instanced, purely cosmetic places that show meaningful achievements through decorations, etc.
The point of these is for players to have visual representation (other than equippable cosmetics) of their adventures on the seas. These wouldn't be meant to escape from pvp, because there would be no point to do so, but rather simply a place that the player could call their own.