Pk protection sold for lant and spammable was a horrible idea.
Obviously you cant make it a pure pve server either.
Suggestion:
Each day, at your first log in to your toon, it asks if you want to have PK enabled or disabled, and that choice sticks with that toon for the rest of the day.
This will prevent people from abusing the PK protections.
PVE players can safely continue playing.
PK can continue pking those that choose to be PK for the day.
If you get spawn camped, you can always wait just 1 day and choose PK disabled for the next day.
Now solution to Partying.
#1 The moment someone turns pink, they immediately get kicked out of the party.
Obviously PK disabled people cannot turn pink. And PK enabled only can become pink from attacking.
#2 A pink person can re-party with ONLY another pink person.
#3 Red players stay as they were.