Paul, first of let me say...NICE TRUCK.
Here is my personal opinion. I would lower it 3" in front and 4" out back. This should give you a fairly level stance (the back might be slightly higher) and shouldn't affect your load carrying capibilities or ride quality one bit.
3" spindles in front (you can get 2.5" spindles too), and a shackle/hanger kit for out back...that'll give you 4" of drop.
If you ever need to, you can install helper bags in back between the spring and frame...that way you can inflate them to allow you to carry more weight in back w/o having to worry about bottoming out or anything like that.
I lowered my truck this way and could tell no difference in handling (it actually got better) or load carrying.