What are the must-have accessories for the HD?

[Rado]

I don’t have one right now but I’m speaking from prior experience. Pulling the air into the bed then pushing it up over the trailer creates a vacuum. That vacuum is drag. Put a topper on and the air flow stays level with the cab then rises up over the top of trailer.
Nutshell = creating better aerodynamics. View attachment 177017


The Blue Mule

Makes sense. If I remember right I think I read that someone with a motor home got a little better MPG when they were towing a car behind them ! And explained it about the same as you did! Forgot all about that till you mentioned it :O Damnnn Im old lol