Chaz: at this point in your build, you could confirm how well your shape is going to perform (or not - don't mean to jinx you!) fairly easily by skinning it with cardboard and duct tape and then tuft testing. Probably take you about one to 2 hours to do & gather the visuals needed to know for sure.
If you do it, have someone follow you with a video camera - or set up a camera on a boom attached to the rear of the truck, shooting forward like I did when I tested my boat tail:
