The classic problem is an RAA reg aircraft which is weight limited but would have a higher legal weight in GA. You are about to cross Bass Strait. Do you limit your fuel load to the RAA amount, or do you fill to the technical safe limit of the aircraft? Obviously the latter is the responsible decision. You will be legal about one hour into the flight once the excess fuel has burned off. If you then have an incident on arrival, can insurance be refused because you must have departed overweight?