I have used the DAC 'campertop tent' on my Element - the midsize pickup size. On the Element this size is workable, but not ideal, since the Element's opening is taller and narrower than a typical pickup. Unmodified it pulls the upper hatch down quite a ways.
I modified mine, by putting in a widthwise tuck, and adding an entension to the bottom. There are some pictures of this on my pbase gallery
http://www.pbase.com/paulj3/ecampcampertop
It isn't as bug proof as I'd like, though I'm not sure how much of the problem is with the coarse mesh or the fit around the sides. Also it is hard to keep bugs out during setup.
I've looked around, and xocom seems to be the only alternative to building your own. However, when I looked at the xocom web site a couple of years ago, it wasn't clear whether they were still in business.
With some sewing skills, it shouldn't be hard to make your own. I've even tried a mockup from poly tarp. Another thing that I've experimented with is hanging a mosquito bar (Mombasa 2 man) over the tailgate opening.
In cool windy/rainy weather, I've found that I'm just as happy sleeping in the Element with the doors all closed, and if necessary some netting over one or more windows. In warm, buggy weather, I'm inclined to use a well ventillated tent, rather than put a lot of effort into improving the tailgate tent.
paulj