The closer the valves are to the bag the quicker of a lift you will get. Try to mount them on the side of the frame near the front suspension. The back if you have a cut through of the bed mount the valves on the bags.
Which valves did you get, I'm guessing from AIM/Chassis tech because of the 8 port tank, but which ones did you end up getting?
Be careful with those SMC, make sure you do not put them in your engine compartment, the heat from the engine gets the valves way too hot. What I ended up doing is mounting them on the side of the frame and I had a cover made and bolted it on the frame to cover the valves.