Bam,the 'voids' are fast disappearing and she does look plenty sturdy.
From your new dimensions,it looks like your new wake area will be about a third of the original.You've exceeded Kamm's 'practical' length 50% frontal area wake recommendation,with length that can easily be removed from the truck,so you have the potential to eventually exceed the drag reduction of any of Kamm's road-going cars.
Cd 0.23 was his lowest drag,built on the Mercedes-Benz 170-V experimental chassis architecture.She'd do 115-mph with 85-hp,and got remarkably higher mpg that the 'naked' Mercedes.
With everything faired in she'll be a real 'Cold Rod,' and the inspiration for a new, feature-length motion picture,"The Fast and the Frugal."
It will be hard to wait for gas station data on the upcoming road trip.
Thanks for all the uncounted hours of 'retrodynamics'.I like to think that you'll have some big grins going down I-10.