I'm not sure TejanoTrackie's TT-setup Visp would agree with you there. Obviously you're gonna suffer if there are long climbs or descents, but I've gotta figure the terrain at the beach is going to be mostly level, with any climbs being of the short (<1/2 mi) variety.

If you think fixed gears are "slower" than geared bikes on flat ground, ask yourself why all the UCI Hour Record attempts are made on fixed gear bikes. I'd want to double check with one of the track guys, but I don't think there's anything specifically in the UCI rules which outlaws derailleurs... just a bunch of stuff about tubing/weight and aerodynamic advantage.