Pseudonyms! In the era of online white pages and easy doxxing I'd prefer to protect my real identity as much as possible. I've scoured the blog for hints at what the business side of pseudonyms looks like. You've mentioned that you can register copyright, open bank accounts, and receive 1099s to a business name. Are there any other business-side considerations, or is it just a matter of how to set up payment?
Alternatively, if you keep all of your finances/paychecks under your real name and just use the pseudonym on book jackets and social media, would this undermine the attempt at privacy? Meaning, are there any public record aspects to publishing that would connect the identities?
You're really talking apples and oranges here. Protecting your identity to preserve your privacy is easy if you never tell anyone anything other than your "nom de guerre" and the concomitant EIN.
Doxxing, which is malevolent, and often done by people with evil on their mind is a whole different ball game. Those people do things like trace your IP address, monitor where and when you post things (including comments) and use the information to harass you.
That's something no pseudonym or EIN will protect you from.
As for public records, there are a million ways someone can find you from a publishing deal. A publisher has your home address, if only to ship you books. And your local paper runs "local author does well; secures book contract" yadda yadda, and those stories are searchable. And if your agent and editor are calling you Felix, and your nom de guerre is Colin Smith, I guarantee you, someone will slip up at some point.
I don't want to make light of your security concerns. It's entirely possible you're dodging a stalker or ex-spouse who has made threats that should be taken seriously.
But, absent that kind of thing, most people simply won't care enough to stalk you or harass you.
I've had authors (particularly back in my pr days) who had to worry about stalkers, or travelled with security. Basic precautions were the norm. Only once did we need the state police accompanying us to a signing. And of course, Mrs. Rosyln Carter was accompanied by a Secret Service detail, but that was again, just business as usual.
One of the leading writers in the crime field writes under a pen name. Everyone knew and no one cared for years. I can still remember getting a query from a writer who told me, quite proudly, that he knew Nom de Plume by his "real name." I instantly rejected the querier as an asshat I didn't want to work with. The querier revealed himself to be someone who knew "secret" (it was hardly a secret) information and passed it along to a total stranger (me) in order to make himself look important.
Being a writer involves opening yourself to the public.If you want people to read your books, you must assume some of them will be curious about you. It comes with the territory. Whether you want to venture into that territory is up to you.