Welcome to the forum.
Ditch the roof rack.
Do not put a bike up there! Stick it inside the car (it's a station wagon!), or get a rear rack so the bike can ride (mostly) in the vehicle's wake where it's going to have a smaller effect.
Sounds like you're considering ditching the sunroof deflector as well. Good idea. Full time aero penalty for what percentage of actual use?
A thought: propping the rear of the hood may intuitively seem like it will help exhaust air from the engine bay, but the cowl area is a zone of
high pressure. You may not be getting the results you're after there.