ok, consider the LOGISTICAL problems of the "floating platform" theory: that is, keeping it supplied with food, fresh water, fuel for the shuttle, etc., while hiding ALL of that from EVERYONE...
even if "the conspiracy" had a secret seaport, they would still have to get all of that from the farms, refineries, etc to the seaport, which would be noticed!
and that's assuming nobody saw the fence and the "no trespassing" signs around the port and wondered who it belonged to...