Fuji has instinct, not insight. He can literally feel where the ball is without seeing it. But that'd do nothing against shots that are hit to a spot you cannot physically reach so AK would definitely work on him. WoI may or may not work, since it seems like the type of blind spot located by WoI varies (can be reach, speed, reflex, etc). Any vision related blindspots would have no effect on Fuji.
Using Rai to return WoI/AK would basically be the same as using Rai to return a shot that goes out of the court. You'd start off in the back wall (so you don't have to run quite as far). At this distance every spot in the court is a blind spot so AK/WoI would reveal no useful information. As soon as you see Atobe hits the ball then you teleport back into the court. Assuming Sanada has only one blind spot, the chance of Atobe guessing correctly is very low so the ball can be returned normally at this point.
That said I suspect tactics that involve running out of the court and back is probably not something they actually do in POT since nobody actually does that, even though with their described speed this is easily doable. Of course this strat would get beaten by endurance issues since Atobe doesn't have to use WoI/AK every hit but to defend against it successfully you must start outside the court so you'd have to use Rai on every hit.
I suppose you can do like start inside court, and then immediately teleport 5m to the side the moment Atobe hits the ball, thus changing your existing blind spot. But again there's no visible cue for WoI/AK, and for that matter it seems like he can actually use it on every hit without any noticeable repercussion, so you'll lose on the endurance front if you've to use Rai multiple times on every hit. Note that it takes more than one Rai to return WoI because you got to use Rai once to reset your blind spot, and chances are wherever you teleported to is nowhere close to returning the ball, so you got to use Rai again, so you'd need to use 2 Rais every rally. There's no way that's sustainable.