Based upon your community shuttle service to Orlando International Airport my recommendation would be American Airlines. Orlando to Miami to St. Maarten. There are two workable flights in the morning to Miami with connection to SXM flight.
The return from SXM will have a long enough layover in Miami to have dinner before you board the flight to Orlando.
A helpful note, book the return flight segment from Miami to Orlando with early boarding. That flight is always full.
You should make it to Orlando with just enough time to catch the last shuttle home.

I take this route with car service from Melbourne Florida 95% of the time in 30 years of trips to SXM.
Safe travels.