All I see is newbs arguing with the more experienced members...which you should listen to their advice.
As for OP's topic, opening a po box under an alias is a no go unless you have a legit fake id. Which is usually risky when doing something like this.
When I opened a PO Box I already had a USPS online account but the made me give my id so they could photocopy it.
6 months down the line I changed my information on the USPS account online which was connected to the PO Box. So when I went to cancel the box in person they were unable to locate my box or my info.
So you can open a box in a legit name then change the info online which will take forever to find the owners info, but they will still have the original photo copied id.
If you do something like have a friend open a box for you, and add your name onto the list of people who can have access to it. They will most likely id you until they are familiar with you and will no longer ask for id which was the case for me.
I sort of rambled, it is possible to open a fake account using a fake info aslong as you have a fake drivers license/id that you actually got from the DMV. but it is very risky.
It is very possible to get legit fake ids, but that is another subject and VERY VERY risky..