Not the same thing exactly, but I'm able to run 2 ecommerce sites with non-trivial sales volumes, by myself.

The two biggest things that make this possible:

a) Email support only, no telephone support (sales or post sales). Not everyone likes it, of course, but if you're determined to be a one man band, it's essential.

b) Automation of every single thing you can. For you, it would be a different list, but I had to automate things like refunds, tracking numbers, inventory levels, fraud detection, etc.

Also consider having someone you trust have access to documentation, passwords, accounts, etc...in case of some kind of emergency, etc. If it's making money, it would be a shame not to be able to pass it on to a beneficiary if you were to die unexpectedly.