Wind sideways sway
Have you considered training wheels, like the ones you had on your first bike? :lmao:
Just kidding. Short of adding weight down low, like skid plates or big jugs of water on the floor, I can't think of anything that will reduce the affects of wind on the 4Runner. Any SUV is going to get blown around in a side wind. It's the nature of the vehicle. If you want good aerodynamics buy a sports car. With a high clearance vehicle you're always going to be affected by wind in an SUV.
Of course, they benefit from tail winds more than most sedans and sports cars. :bravo: