A LinkedIn profile with a fairly recent photo?
Professional email? I have a second email account with no connection to the hobby for a discrete and brief exchange.
A collegiate (.edu) email. But hey, if you graduated 5 years ago, that might not be sufficient, even if you've kept the email active.
I could discretely call and ask for you at your desk through the automated attendant, dial by name system or receptionist. Even if you're not there, I could and leave a message for you to retrieve.
A photo of you on an organization or company website,
An article written by you that includes a photo?
Certain hobby board memberships. Those will be considered on a case by base basis and even then there has to have been interaction between you and other companions there. Typically P411 and RS2K always work.
References from companions you've met before. They have to be serious companions when real internet footprints, not a collection of free ads/posts.
Your drivers license and a selfie. This should be considered as one item, not two.
If you can think of something similar to the above that I neglected to mention, tell me about it. Maybe that will work for us. I'm sure we'll figure it out.