Leveling truck

Why not just add a couple extra springs to each side. If you shop around that should only set you back roughly $500.00 but would have excellent control. I did that on my 98 Tacoma when I put on a heavy duty contractors aluminum large cap which I installed in 2000 and still own and it drives great. I have not done it to my ram yet but will this spring.

You're describing an appearance like it's an action. You want to carry extra weight and engage the overloads sooner. If you're already engaging the uppers then yes, engaging the lowers sooner will help with sag, and sway.
My 2500 Dodge doesn't have upper overloads like the older trucks and no holes in the lower spring to easily attach a wedge or stable load.
What I plan on trying this year is using plastic felling wedges on the lower leaf. They match the angle between the leafs pretty closely and are about the right thickness.
To attach them, you can screw/bolt them through the hole in the spring. I'm considering dado ing a groove in the wedge and hose clamping them to the spring leaf. If it still spits out the wedges then maybe grind a slight "catch" in the leaf to keep the hose clamp from sliding.
It's pretty redneck, but for the little I use the camper, if it works, it's a cheap solution.

Thanks for the replies. I have the upper bumper stops so I like Towpro's suggestion - decent price. I thought I read somewhere blocking the lower spring will level the truck and the upper overload smooths out the ride/decreases sway. I'll experiment by putting a pressure treated 2x4 wedge between the lower spring, load camper and see how it looks/rides.

I have a 2500 that only have lower overloads,and put hockey pucks as spacers. full one on the bigger opening at the rear and 1/2 one at the front. screwed in with short thick lag screws,thru the hole in the end of the spring. worked great.

if you have upper springs that hit a perch on the frame as your loaded, check out these. http://www.amazon.com/Energy-Suspension-9-9109G-Heavy-Duty/dp/B000CN5GRC

I ran them on my 2006 Dodge, and they were still holding up well at 60K and 9 years when I sold it to my brother.

I have always heard upper first.