Most safari vans in Kenya have an opening top like the one in the picture I have linked. While I have never seen one being installed, I can pretty much guarantee that these are "fabbed up" from local materials and with no special hardware. When you look at them up close they are not all that great of workmanship, but from a distance they look just fine and they do the job of raising the roof. Anyways, food for thought....
Masai Mara Day 2 - 03, Masai Mara, Kenya
Masai Mara Day 2 - 03, Masai Mara, Kenya