slick sprite
 

found a really slick looking sprite
California Streets: El Segundo Street Sighting - 1961 Austin-Healey Sprite
anyone know if this is a commercially available bonnet style?

That's an odd little duck.

bonnet
 

One consideration is,that even if you get one,your drag will still be higher than any pickup truck (Cd 0.38-0.45).And that's with a roof.
The Sprite's windshield is the culprit.
A spyder half-bubble screen and head fairing could get you to Cd 0.31,but you'd be required to wear goggles,unless the screen was laminated safety glass.They're not available.