Of course we thought about that! Here's what you need to do, within event:
Go to Other Settings
Under Registration Access, change the option to Private
Assign a password and when the privacy will end.
If the event is 100% by Invite Only, set the date to the same date you plan on closing registration
If the event is for Pre-registration, set the date to your desired date before you open it to the public.
Add a password that you will share with your invited athletes.
Your event will still be listed in the event directory however if anyone clicks Register, they will be asked for a password before they can proceed to sign up. As shown below.
Note: This also applies to the embedded registration form as well
