It looks like Florida does indeed have some pretty high wind speeds. Mind you, some of those numbers are for maximum wind gusts instead of sustained speeds. See
here for more details.
Knowing a little engineering, there is likely a good number of modifications to the wind load. Things like building height, building/material smoothness, shape, site wind exposure, occupancy type, etc would all modify the actual final wind speed/load. For instance, trees/bushes can significantly reduce wind speeds for a distance five times their height; also the wind speeds on the map are at 33 ft above the ground. An experienced and knowledgeable professional engineer familiar with Florida wind considerations is in order here.
As with Bob, I'm not sure if you're talking about a manufactured/mobile home or an RV/5th wheel trailer. In either case different rules probably apply than for typical residential construction (manufactured homes have HUD, trailers are usually temporary dwellings). I'm going to guess the county guy just meant it was _easier_ to permit the trailer, not that they'll actually stand up to the wind. And that would be bureaucracy.
A simple concrete foundation could actually be pretty favorable. If you were in a cooler climate, in-slab
would be nice. In florida, in-slab cooling might be more appropriate
But if you're sitting on the ground directly, the thermal mass might be enough to keep you cool.