The map pack does not cross the Howard Frankland for you
One verified address in Hillsborough County will not put you in the map results a homeowner sees in St. Petersburg, and no amount of on-page work changes that.
Local results are built around proximity to the person searching. A dealer with a shop in Brandon can rank well across the eastern side of the county and be effectively invisible in Clearwater, which looks close on a map and is not close at four in the afternoon.
The options are limited and worth being honest about. A second real location with staff, signage and its own reviews can earn a second pin. A mailbox cannot, and the attempt tends to end badly. In most cases the better play is to treat the map as a Hillsborough asset and win Pinellas with everything else.
Everything else means service-area pages that name St. Petersburg, Largo and Dunedin with real jobs behind them, and review requests from Pinellas customers who mention where the work happened. Organic listings, unlike the map pack, do not care where your office sits.
Set the expectation internally too. If half the marketing budget is chasing a pin the format will not hand you, you are paying for an outcome that is not available.