This type of setup is certainly not new to aviation.
Good friend of mine years ago outfitted two DC-6's with extra cabin tanks (2000 gallons) , for a south pole series of flights.
The extra fuel was used to re-supply ground tanks, and in addition was plumbed to feed the engines enroute.
This all worked fine until one day the bonehead pilot, who insisted to keep the mixtures in autolean during approach/landing (ISO autorich, as the checklist mentioned), wanted to overshoot, cobbed the throttles, found no power available, and crashed.
Everyone walked away, but the aeroplane was a total loss.
Moral to the story...listen to the Flight Engineer.