I wouldn't even run coils there overrated....
Honestly my experience with air shocks for the rear was terrible. Was never happy with them. In order to achieve the nice level ride height I wanted I ran them at the lowest air pressure (20 psi) and that was way too soft and I'd always have my axle smack the frame. With more air than 20 psi they were super bouncy going over bumps. I'd run normal drop shocks on all 4 corners and save extra money for helper bags
Agreed.
Another point that I want to make is to NOT use the Belltech 'Nitro Drop 2' shocks. Trust me on this one... They ride great on a perfectly smooth road but, at freeway speeds, if there is a change in the pavement height or a bridge transition that isn't perfectly smooth with a flip kit, notch, drop spindles, dropped coils, short sidewall tires, etc. these shocks do not respond quick enough to keep the truck off of the stops and also in my case, the top of the tires away from the top of the front fenderwells.
For the front, if you use dropped spindles and don't cut the coils, you can use a standard size shock. You could probably use standard shocks with an inch of drop cut from your existing coils.
For the rear and your flip kit, I recommend a set of "load bags" and a good 'quick responding shock'. I have the "Air Lift/Slam Air" bags on my truck, keep them at about 12 lbs. empty and it rides good. Then, if I am going to pull the boat, I just add some air for added support and it works well.
Like blue_92_sierra said.... You don't want bounce! And when the bed is empty with air shocks or even load bags, with a little too much air, it'll bounce!