Okey-doke.
That covered, look at
Taking aim at air drag again. Ignore the 20% lost to the trailer gap. You still have the proportions of front
vs rear
vs undercarriage. Things like the high momentum mudflap and vortex strakes apply to you situation more than something borrowed from race cars.
For the fairing for over the windshield, look to Luigi Colani's trucks.
https://ecomodder.com/forum/showthre...html#post70669