Here's some pix to give you an idea of a very sturdy build for a pick up. I run this bad boy down the expressway at 70+mph enroute to shows and have never had a problem. I will say that for safety sake, I pop a couple of long wood screws through the fin, right where it meets the base and into the brace wood. It was measured to fit precisely in between the slots from left to right and top to bottom. The wood are 2x6 with long bolts and nuts holding it all together.
It stands about 6' out of the bed of my truck over the top of the cab and catches a lot of attention on the way to shows that I've run it to in MI, WI, OH and IL. Beats the crap out of a sindow cling fins up sign that most people have.
Lastly, I'l say that I run it TO the shows only. I take wrenches, a ratchet and hammer with me to take it apart before leaving the lot after the show. It slips right under the braces (still together) into the bed of the truck nicely, then I load all my gear on top of it for the trip home.
For a car, I'd recomend building a base out of pvc and wrap it in that foam that you wrap plumbing pipes with so it doesn't rub the roof of your car all up.
Good Luck!
The fin decoration is a nice compliment for a show, but my plate is with me year around.
