I haven't experienced PvP on this game, but seperate to what there is already in-game, what about a flag system that changes your status from PvE to PvP? This could also allow for PvP to happen once you hit the mainland? In another game this is a very fun feature that encourages guilds to form small groups and head into battles early on into the game.
https://wiki.albiononline.com/wiki/Faction_Warfare
https://wiki.albiononline.com/wiki/Faction_Warfare