We'll most likely just have a login system whereby all whitelisted users can login to PD3 using same credentials as PD2 for testing. You can get whitelisted by being active in chat/community

I really like this system so I can keep my PD2 ID.
The whitelisting rules seem to be highly variable, are there guidelines posted? I'm whitelisted, but it frequently comes up in chat from new users.
Good Luck!