Rock sliders are more an invention of the rack crawling community, but we saw some benefits of having these. The main purpose of the sliders is to protect the rocker panels on the truck. If you smash these you have a good chance of not being able to open the door and it is a very expensive piece to fix. Secondly this can function as steps to get into the car, but even more importantly to stand on when opening and closing the tents. The steps can also be made into tree sliders (much like a rock slider it just protects from side impacts.
Biggest decision when making rock sliders is how will they connect to the vehicle. A lot of people simply weld these to the chassis rails. This cheaper and easier but presents problems for painting or repairs later on (have to remove slider to get to the exhaust). We decided to use plates that bolt accross the chassis rail. Basically sandwiching the chassis rail, but not drilled through the rail (above and below). We used three arms on each side to connect the slider to the chassis. It was a bit tricky to shape the arms around the exhaust, but it worked out fine in the end.
Thoughts afterwards: If I had to do this again, I would go with heavier steel. I used 3mm but would suggest at least 6mm. It adds weight but you will be sure that the slider does what it is supposed to.