pvp server isn't just instantly pvp. pvp is the whole concept of the server for example don't know if you knew this server but l2gang was a pvp server back in the past i was playing there since it was epilogue client, it was pvp server but even after 1 year playing there you still had things to do since rb jewels were retail (drop from bosses) and we had epic fights in raid zones to get them (about 1k and maybe more each time) usually we were fighting the top 3 clans back then (for those who remember 7hills, riders and anarhcy) and also blessed scrolls were hard to get you could only get them from bosses as well.
Also L2FreePvP was instant pvp server but you had to fight for fame to make pvp items, for gcm to make +30 skills it was a long term server as well with high online.
you can make a dressme system working with retails items which means 0 custom and every player has its own style as well, with custom items it's kinda the same, they will all have the same look it's just that they will have 4,5 more options but using the retail armors you got way more choices and in my opinion it's way better.