I ran an 8 hour long Freebooter session this weekend at the Ludesco convention in Switzerland. The three courageous players had much much fun building the setting then exploring one of its islands in search of Mayondinca artifacts and ruins. Some epic moments with an elemental-driven typhoon, angry merfolks pursuing them through half flooded ruins and mangrove, strange but finally quite nice vegepygmies, old mayondinca legends becoming true again and a demon accidentaly awaken from eons of (troubled?) sleep killed with the newly constructed balista for their pirate ship.
Mayondinca = Maya + ondin (=merfolk in french) + inca
8 hours! wow! sounds like a really fun time.
Typical 4 hour con slots are not really enough to do chargen, world creation AND have a fun 7-10 encounter adventure. 8 hours definitely would be.