I too have an '06 Dodge Mega, 2500, and a sled deck.
Airbags are a must for us with the short-box. The weight center of the deck and sled combo is just barely forward of the rear axle. I also put 480 lbs of sand tubes in the bed, up against the front of the box. The extra weight doesn't matter too much, but being forward of the rear axle helps to keep the front end from wandering in corners. It still wants to push a bit if you drive hard.
The bags helped level the truck front to back, as well as side to side stability. I have the firestone ride-rites, and I put about 60 lbs in each bag with the sand tubes, and two sleds. Just make sure you install the bags with separate fill valves-don't split a single fill valve, I've seen this done, and it still helps with the extra load, but doesn't help with side to side stability. I put my fill valves inside my fuel fill door, above the fill spout, and it's a nice location, protected fro mud and snow, and easy to get to.
If you don't have the diesel engine, your front end will feel that much lighter as well.
Also, I make sure I run load range "E" tires, and put the rears up to the max inflation when I have the sleds up there, I have 35x12.5 - 18" tires, so I don't have a huge sidewall, but that extra pressure makes a huge difference. (they max @ 65 psi, and w/o sleds & deck, I normally run 50psi).
Send me a PM if you have any questions. I love the combination for local rides, it works well.
PE