My paperless monthly bill needs to reflect that Billing address and usage address are different.

Residences in the town I live in dont have mail boxes. If you want to get mail, you have to have a P.O. Box. On my monthly bill, it wont let me enter my P.O. Box as my Billing Address. I Live on a Boat and although there is a physical address to the dock, Thats it. Now the real issue. To get a real Id, My bill needs to list the Usage address as well as the Billing Address which are different. My P.O. Box is my billing address and it wont let me enter that in change of address update form. I've been jerking around with this issue for a couple of weeks and its old. Any help would be appreciated