If you're in the US, you can use any address you can receive mail at (work, a PO box, mail forwarding service, etc). I used a cheap mail forwarding service (it actually doesn't charge a monthly fee, just shipping and I never get mail there anyway). The important thing is to get this setup before you even get your FRN because the change history of your license is also public, so once your address is there, it's viewable forever.