How is the screening process different for the self-employed vs for people who 'punch a clock', who have co-workers and HR people who can be called to verify their identity?
I usually have everyone send me a blank email from their work email account (to a more discrete email account obviously, not the one I advertise and do business with). I research their company to make sure it's an actual registered business and not a fake one made up to trick me. I won't give away my exact secrets about how I do so on a public board, but it's pretty much the same whether you have your own company or you work for someone else as far as I'm concerned!
Of course sometimes with small business owners, artists, etc., we have to get a little creative about how to verify. But most of the time it is not so complicated as long as the self-employment is real and not a recent change as of the last year or so.
I think I have an idea of your verification method for a business but what if a business's information that is public only gives the name of the registered agent and not the actual owners
P411 Sounds like the way to go.