Aha
I finally had time to play when the dogs woke me up at 4:30 am so I finally figured out how to make the Aimoo site Private
Aimoo support did reply almost immediately after I requested support.
YES I have tested it. I created a user name called emmstest and emmstest2 and was able to deny advanced membership and joining the site to the 2nd user name.
Played with a custom background but it might be to busy depending on your screen size
I'm on 1280x1024 but it might block stuff if your running 1024x768