Yup, used to do it this way in the early surfski days. It’s going to be a 1/2 mile or so of mostly pumping though before you get any glides. Then it gets REALLY good by the time Miller island ends and the river comes back together.
Can’t recommend Celilo to Rufus through Hells Gate canyon for supfoil though. There’s one particular horror story I remember hearing involving a lot of walking barefoot on the WA side gravel road (ask at Big Winds) 
Highly recommend it winging though (or any other craft).