I don't recall seeing this discussed before, so I'll just throw this out and see what you think. Using the website
http://www.flowgenerator.com you can create a 2-dimensional video of the air flow around your trailer. First you must create a bitmap of the trailer, using Microsoft Paint for instance. You upload the image, wait a few minutes, and download your video. Here's the image I used,

, with the video available at
https://youtu.be/GoRRqOst-OA When I included the ground, it messed up the whole simulation, so this isn't terribly accurate, but it is interesting.