The general policy for PO boxes post 9/11 is that it
a) has to be in a city in which you have residence
b) if not, you must show proof you are a resident in that city.
I see no reason in hell, you need a po box that far away. you are no safer, and in fact, may even draw more attention to yourself. But what you need are two IDs, one placing you at the address on your Drivers license (DL) and another verifying you live at that address (A utility bill or rental agreement, for example). In the case you are taking out a PO box in another city, you have to go to your local PO and show them the same two IDs described above, to get them to "verify" you qualify for a PO box. Explain to them that you need or want a po box in this other city, and they should be able to take care of it. After this, take those same two IDs to this new city PO and things should be in order.
NFG