Assuming your truck does 60 mph, it appears it does[1]. 80Hp for rolling resistance, electrical and all other losses, 120Hp for aerodynamic drag.

Of that, cars modified to be super efficient (eg. [2]) can get the Cd down to about half (from about 0.31 to 0.17). Trucks could probably achieve an even greater improvement, because production cars already have a slanted windscreen and rear trunk.

So, overall, I stand by my claim that energy use of trucking could be reduced by about half with aerodynamic techniques.

[1]: https://theicct.org/sites/default/files/publications/AERO_RR... (figure 2)

[2]: https://www.aerocivic.com/