I believe there's a Mark's Porsche in Ft. Walton on racetrack road. Although he specializes in air cooled Porsches, I have seen a few Boxsters in his yard. Also, Destin Porsche (on Main Street, where Destin Motor Cars used to be) should have opened up their specialized porsche service center now. I don't know how new your porsche is, but they should be able to handle any problems your boxster has.
Capital Eurocars in Tallahassee does a great job servicing. Bruce Parker is the dealer who primarily deals with customers in the Seaside/Panama City Beach/Destin Area. He should be able to help you out too.