From what I have seen so far, electric trucks are best used in urban fleets where the top speed rarely breaks 45mph, range between work related stops is low, and manual labor at the destination site is high. Think furniture delivery, warehouse distribution to sales outlets, things like that.
Best configuration is extremely high and aggressive regenerative braking so that the instant your foot is off the throttle, e-braking is applied. It takes a learning curve to get good at it, but the goal is to avoid using the disc brakes at all. Wind resistance becomes brutal to vehicle efficiency past 45mph, so surface street travel is more energy efficient than highway as long as e-braking is your dominant means of coming to a stop at intersections.
Harvey and Florence, living their retirement dream with a fifth wheel, are not going to be well served by an electric rig at all.