I have a 2003 Silverado 1500 and I recently purchased a pop-up camper that weighs roughly 1500lbs.  I usually tow a 19ft bassboat along with this rig too.  The truck has plenty of power, but i'm squatting pretty good when loaded and want to get back to a level ride when I'm loaded down with camper and boat.  What are some options I can look at?  I've heard about the timbren cushions, air bags or adding a leaf.  What are advantages/disadvantages to each or any other suggesions?  

You do not want to use timbrens or air bags and the reason for this is that your leaf springs not only support load but also control axle wrapup for wheel torque. Added leafs improve control of axle torque with a heavy load, the other two do not. GM has reduced true spring capacity on 1/2 tons a lot in last 20 years while marketing them as better haulers. Thru 87, 4 heavy leaf plus a boost leaf was the standard for a 1/2 ton with 5 leafs and booster a option. In 88 thru 99 3 leafs plus a booster was the standard and only configuration. Starting in 99 with Silverado GM further reduced springs to 2 leafs plus a booster to give it a more car like ride for sales. You are in a tricky situation here because you are overloading your chassis if you are carrying a camper in bed and towing a boat too. Even if you add leafs you still have a lighter chassis as GM stopped using same basic chassis on 1/2 and 3/4 tons after 87 and your rear axle is only rated to carry 4000 lbs tops. With a in bed camper and boat in tow you can easily exceed the capacity of rear axle which while is may not break it will shorten its life. Then if you have the misfortune to get in a wreck with it like that, the lawyers could have a field day with you. You really need a 3/4 ton truck here. This aside, if you want to try to make this work, go to a spring shop and have them add a few leafs to each side in rear (they do this a lot) They will put them into stack and it will look normal/OEM but there will be more leafs in it. It will improve stability with a load and torque control of axle. DO not use bolt on add a leaf as they are a poor solution and no  need to replace entire spring stack because adding leave is cheaper and just as effective as buy new complete springs with same amount of leafs.  

Thanks for the info.  You basically confirmed what I've been thinking all along.  I was hoping to get by with a 1/2 ton for the gas mileage.  Do you know any real world specs on what I could expect with a 2500HD 6.0 loaded wiht camper/boat?  I've been told they get 12mpg loaded or unloaded, but have yet to get 100% confirmation on that.  Currently I get 11mph highway with my camper/boat setup on the 1/2 ton.  It's a tough call b/w diesel vs. gas with these gas prices.  Looks like i'll be looking for a 2500HD in the near future just not sure if it'll be gas or diesel.  

I would suggest a gas one. The reasons for this is gas truck weighs about 500 lbs less, (diesel and gas models have same GVW rating too so this is lost "legal" payload) they can be had for really low prices today new and used, it is a lot simpler and cheaper to fix a 6.0 than a Dmax and finally diesel is never going to be cheaper than gas again and stands to cost a lot more at times negating any MPG gains from it in overall operating costs. For it is worth, my son is a assistant manager in a oil change shop and he sees a lot of 350's with 300K plus miles on them from fleet usage doing well and newer 6.0's with around 200K and more doing well too. He had one 350 in last month in a 2000 1 ton van that had 565,000 miles on it and still going strong with original engine and tranny.  

Thanks for the info.  I think i'll start looking since I head south on tour in another month and want the rig ready to go.