Change your PO to Alton Bay and get a PO Box there. The office is open from 7am-7pm seven days per week.
While on your extended stay at the lake, when you go to the PO , you get a nice boost ride to get the mail, get lunch (eventually) at the Bay, then a nice leisurely ride back to the island. May even want to stop at West Alton or Minge Cove for gas.
I know, too late and too much trouble to change again, but then again, there's always next year
.
Dave