That's a project I haven't got off the ground yet. I set up various sized blocks on the hood and slid them forward and backwards to check visibility. It is practical for light weight, bulky items. The military mounted gas cans there during WWII. I wanted it for folding chairs, rifles, metal detectors and the like.
I think I could see over 14" stack of blocks without a visibilty problem to about 30" from the WS. might be a good place for off road lighting too.