trailers
Something like this . . but in actuality an inflated fabric stretched over a framwork on the trailer frontal area, (not just a gravel protector as the lower panel). My thoughts were to do both. Nose-entry, and "belly pan" (versus nose-entry and
big honkin' mudguards hanging from truck rear)
The reference was for an inflatable trailer nose, from England IIRC, ca. 1982 in Pop Sci mag. Naturally, I can't find my own link, but it is referenced in a thread on this site.