I, for one, had my '62 bus up to 103 mph once and regularly cruised at 70 (it was modified a bit). But yes, the very early buses with 25hp/36hp had a top speed of 55mph.
What's your research in regards to the air flow and pressure zones? It's a pretty straight forward bernoulli effect at play. The air traveling faster (over the outside of the vehicle as you drive it down the road) creates a negative pressure zone relative to the slower traveling air (any place within the vehicle outside of that flow). You might get lucky and get neutral pressure if there's enough of a turbulent zone around the car at that particular spot on the vehicle, but I'm not sure. I know in older cars that was an issue, but automotive design has come a good long way since swing axles were generally accepted as awesome. Having never seen any sort of air flow research done on a 4Runner,
I can't speak authoritatively to one case or another, but I would be completely surprised to find that is a high pressure zone... Basically, it's pretty slab sided and straight, and you're putting a scoop right in the middle of a big relatively flat surface parallel to the direction of air flow. If it's designed well, the fluid (air) will hug the surface and you'll be scooping from a low pressure zone, if it's a bit more haphazardly designed (a bit more likely), you'll get a good bit of turbulence from the side view mirrors.
What you COULD do to put the scoops in a high pressure zone would be to stick them WAY out there. You're still going to be fighting the pressure drop from the turbulence generated buy the side view mirrors, but it would reduce the negative effects of attempting to put functional air intake scoops back there.
That said, you're still going to be fighting the plumbing deficiencies. Fluids don't like turning sharp corners... Also, and you can try this for yourself, get some very thin tubing (no more than 1/2" in diameter if it's really long, otherwise think really long drinking straw). Cut a relatively short piece off one end, and leave the other long. Attempt to breath through the short tube, then try the long tube. It takes far more effort to move the same volume of air through the longer tube that it does the shorter tube. You're effectively trying to make your engine breath through a really long straw. Even IF you solve the air flow/pressure differential issues at the scoop, you've lost your ground with the plumbing.
A turbocharger at the scoop end could potentially solve the issue I suppose, but what a lot of effort and expense to just "look cool"... I'm no stickler for convention, but some things aren't done simply because they don't work.
