atm im running a zombie server where you have to buy stuff from the town to progress
however the NPC's there are a little unpredictable and you cant defend yourself against the zombies in there without getting shot
so if  you could somehow make a new zone type that alllows for PVE dmg but not for PVP damage it would be amazing

i see ofc now that the problem probably is if your turn of hostility to players causing PVE damage how do you make the gaurds defend themselves? well i dunno, but if you could it would be awesome

You need to use botspawn plugin and ensure that you have excluded the town from spawning zombies, thus ensuring you don't have to deal with them there. If it is PVE you really don't need zombies at this location anyway.