Assuming you have the height off the flatcar (another assumption) and any dunnage bracing, do you want it to look like loose draping falling down, or drapes with straps over the cover in specific locations, or do you want it to wrap around and under the stabilizer with loose ends draping down? Are you modeling after a picture that you could share?
I can give it a go, but I need a step file (.stp) that can convert into my CAD tool.
I believe you have my email, if not, send me a PM.