Air Rhodesia, during the UN Rhodesian sanctions, buying a whole fleet of Boeing 720s from a dealer in Basel, Switzerland who had them up for sale from a Scandinavian holiday charter airline who had upgraded to newer aircraft. Front was that they were for a new airline startup in Paraguay. Paid cash for them, flew them off to Las Palmas, flightplanned for an evening departure for all of them to South America, set off with full tanks into the night, but landed in Salisbury, Rhodesia, and brought jet operations to Air Rhodesia. Real Boys' Own story buccaneering stuff.
Then what about Hank Wharton ? Every grey market operation going !
Without a doubt the centre of operations for your stories used to be, and to an extent continues to be, Miami airport, especially the ramps on the north side with the various independent operators and the local freelance crews who knew the interesting way to the Caribbean and Latin America.