The camper package gives you higher rated front springs (not sure about pre-2005), front and rear anti-sway bars and rear upper overload springs.
If you look at the rear overload springs, they do not engage until you get 3" or more of suspension compression in your leaf pack. The first thing you want to do is to get that upper overload working sooner. You can do this using taller spring pads (like Torklift's upper StableLoads) or putting a taller block between the main spring pack and upper overload so it contacts the the OEM sooner.
If you need more spring capacity, you can have the flat lower overload springs engage sooner by putting in wedges (like Torklift's lower StableLoads) between the the lower overload springs and the spring packs.
The two above modifications will use your OEM springs to their full capacity. Using this setup, it handles my heavy Arctic Fox without additional help. If you need more capacity, you can add air bags, add additional springs or replace your spring pack. I use pressure in my air bags when I tow and like the ability of being able to adjust them based on how much weight I hang off the receiver.
Remember that your current axle rating on the sticker is probably limited to your current tires and rims (the Sterling 10.5" is rated at 9750 lbs). If you plan to load rear axle more than 7500 lbs, you will need to upgrade rims and tires since that is the limit of anything the OEM provides. I was able to distribute weight to keep it under OEM maximum ratings, but it was too close for me to feel comfortable doing trips as far 5000 miles plus it was too much too work to make sure I was properly loading my TC and trailer properly to avoid going over ratings each time I changed what I wanted to carry. I went to 19.5" wheels which allowed to me to get the full 7350 lb capacity out of the front Dana 60 and 9000 lbs out of the Sterling (limited due to rim capacity).
