They're stored on each server. You need to play on the same server(s) to take advantage of tents. A good idea would be to gather multiple tents and spread them out across a few servers all in the same spot. You can essentially move items from one tent on one server to another tent on another server by logging out after grabbing things and putting them into your inventory (since your character inventory isn't per server). Takes a few extra steps but still works the same as having one tent for all servers, you'll just need to find multiple tents. And if one camp on one server is compromised, you won't lose everything since you've established a camp on other servers in the same spot as well. Though it would be best to make your camp on inconsistent servers, ie: one on Dallas 11, and another on Virginia 1 or something. As opposed to one on US1 and another on US2. Because if someone found your camp and it was large, they might server hop to similar servers to see if you set up camp in the same location on those other servers as well, if they were really determined. But the risk of that is low (no one is going to bother searching other servers for your camp if you only have one tent), and if you hide your camp well enough, odds are no one will find your camp in the first place. But either way, it's a good idea to spread your camp across multiple servers.