I have been wanted to get an aero cap for my truck for a while now. I used the ecomodder tool to get an idea of what it should look like.
.Here's the proof of concept from xps foam, glue and paint. I hope to use what I learned from this versions and build a better one:
Tuft test looks pretty good for a first crack.
Tuft test Video:
https://photos.app.goo.gl/Pp9tYJTwWnyYEpcbA
Hope to get A-B-A testing on version 2 as the weather warms up in Michigan.