Halve the cost? Is the pilot and copilot that much of the cost of a flight?
Even if there are three crewmen (pilot, copilot, and flight engineer), They couldn’t add up to more than $500,000 per year. That is a fraction of the cost of operating the aircraft.
The most a crew will cost is $600/hour. Any savings more than wiped out by flying at 20,000 feet vice the mid to high 30’s. 20-25% fuel burn penalty for going low. Not sure what their target burn rate is, Amphibious makes it cost more, as well.