[trikkonceptz]

If your class 8 is the typical semi here in the states then here are more suggestions ...

Fenders for the rear wheels of the truck and perhaps trailer. Design fiberglass fenders that cover as much of the wheels as possible, even side skirt style, thus reducing air turbulence from that part of the truck.

Also are you running dual wheels on the tractor or a single per axle? The single wheel may appear to be more wasteful but is actually a more fuel efficient alternative to running the dual wheels on the tractor. It also reduces weight by eliminating an extra rim & bead lock ring.

If you do not run these trucks at their full 80K pound capasity all the time I always thought a bounce house like inflatable bag that could fill the gap between the cab and trailer would help improve air flow over and around the trailer, using hot air from the exhaust to keep it inflated with a small exhaust vent for when the bag is compressed on tight truck turns.

More to come ...