The first change would be that anyone in combat (No matter who started it) would not be able to enter gate that gives visitor debuff. The second change would be that every character gets to choose one "claim" to allow them to enter while in combat. This could be called their "Safe Haven" or "Home." They could only have 1 at one given time. Once they enter this plot they are given a debuff called "Yellow Belly" which would not allow the character to log off or use Charter stones. This buff would last for atleast 24 hours after entering the plot WHILE in combat. The time would extend if someone was seiging the claim they have set as "Home." However if the player is no longer on the plot then the buff would expire as normal (24 hours). The "safe haven" could not be changed but every so often (Maybe a day or week cooldown) and can not be changed while the character is in combat or if they have "yellow belly."
The first part of this idea can be skipped over of course and keep the combat and visitor gates the same. I believe "Yellow Belly" would fix safe pallies because if someone was chasing them and they hide in a small 5x5 palisade the chasers may not be able to follow but they can definitely siege it without fear of the "Yellow Belly" escaping by logging out or teleportation.