Is that all I need just to proxy through nginx, that's what I'm currently doing, I saw that plugin in settings and thought I was doing something wrong. I just wanted to confirm I'm doing everything properly.

All I'm going to say is that you will be mistreated if you use MyBB (by their community). I'm not going to post the link to my rant here but send me a chat message if you want to hear more about my horrible experience.

So far so good