Working out here in Arizona, killer exteriors are pretty much expected... I've even been in studios where equipment malfunctions from the heat. From an AC point of view... you can't have enough canned air. Always have a courtesy on standby for the camera... assign a grip to making sure the camera is covered in between takes. On one show, the G&E guys made a great little rig that had a basket of dry ice in front of a handheld fan directed through a snoot of black wrap. I'm not sure how practical that is in the middle of the Sahara, but it really helped the camera in the heat. Keep the film in the coldest place you can... put it in a cooler if necessary. Drink a TON of water and keep as much of yourself covered as possible... make sure it's something breathable like cotton. Apply and reapply sunscreen all day and have the occasional salty snack, it'll help retain the water. Space blankets are great to cover the camera if the camera is on standby for a while. As far as any kind of permanent covering for the camera dust, heat, or otherwise... I've never been fully satisfied with anything I've seen. I think that unless it's water... your best bet is to just keep it uncovered while shooting and get it into safety when you're not.