Mind you, my rotary is not flying yet and I have a Canard design but I often wonder why the RV guys don’t relocate the radiator and use a P-51 style scoop?
I’ve seen many that have the radiator almost perpendicular to the direction of the inflow.
I would think that a radiator mounted just behind the seats would give you the distance to properly expand the air and recover the pressure more efficiently.
Just thinking out loud ......
T Mann