Tutorials on mounting double hump fenders?

It will take two days at least. No two trucks are ever the same. Measure twice drill once. Use at a minimum of 1 2x4 between the tires and the fender wit the suspension down, for clearance. You may be able to start at the quarter fender mounting location.
I know at times they are necessary, but fenders are a pain. Especially double humps. When doing brakes or a wheel seal you are working in what seems like a culvert, and you will try to stand up at least once. While in the culvert.

 

Some of the plastic double hump fenders can be quickly removed off the mounting posts by loosening allen screws. All I will add is try and use existing holes in frame by cutting huck bolts with cutting torch and chiseling the bolt out of the frame rather then drilling new 5/8 holes through double frame. If drilling is only option renting a mag drill will save your wrists and a whole lot of time.