A siphon uses gravity, by definition. I would rather not undo a bunch of over-center binding straps on my 11' roof and carry full jerrycans down a ladder and then manually lift them to pour them into fuel tanks, then climb back up the ladder to replace them. I think siphoning will be quite fast with a 7' pressure head, in the rare occaison I have them filled.
But I think your invention is fantastic for blitz cans, they leak the most when emptying.
How does air ventilate into the can with your invention?
Charlie