Targa kits for vans and trucks are available thru the aftermarket. It would need to be modified, but probably not a lot more trouble or expense than t-tops.
Damn, I never thought of that. If I ever get the car to the stage where I can do body mods just for the fun of it, a targa top is high on the list. Was going to design it from scratch; never occurred to me to hunt down a kit which was "close" and modify the kit.