https://ecomodder.com/forum/member-a...ing-effect.jpghttps://ecomodder.com/forum/member-a...g-rig-aero.jpghttps://ecomodder.com/forum/member-a...ilkisons-t.jpgAn inflated structure can serve as both a tail, or a gap-filler between Moby and a trailer. According to NASA, this alone is good for a 16% drag reduction.
Here's a UK product which never made it to the USA.
https://ecomodder.com/forum/member-a...l-trailers.jpg
Here's my first inflatable, which helped push SPIRIT to 32.5-mpg @ 65mph.
How you do your attachment is going to decide the engineering.
AeroStealth has a Prowler 5th-Wheel we're wanting to boat-tail. We think that rather than drill into the trailer, it will rest on, and be clamped to the rear bumper, with tension members running forwards over the roof, using the roof curb of the AC unit as a cinch point to hold the tail snug. ( no holes).
This arrangement also allows us to 'picture-frame' the 'mount' if we like, hinging the tail on one side, which, when swung away, would allow access to the roof ladder.
On the 8' dimension, W.A. Mair's boat tail contour, sides and top would be a known quantity. NASA's tail is similar. As mine.