Hello WildWalderland,
Welcome.
So I am the happy owner of a '17 Colorado Z71 Crew diesel. I have a FWC Fleet flatbed model. A bit heavier of a camper for sure, but realistically pretty close assuming you aren't getting a "shell model". Got the setup in Dec/January and have had plenty of time to get it dialed in and to do some significant road trips. 7,000 miles with the camper loaded.
I think a lot of how you choose your upgrades depends up your realistic use, budget and expectations for ride quality and durability. The biggest battle with any camper is the body roll caused by the additional weight. The more twisty the roads you drive are the more you'll appreciate the suspension upgrades. Plenty of folks put campers on mostly stock suspension with just airbags and are just fine with the ride on their local highways.
I've documented some of the weights and was surprised how quickly it adds up. As many on here have stated. The thing I find really interesting is how the front axle bears basically none of the weight of the camper (on the scale). I've weighed our truck axles with just the empty truck, truck with empty camper and fully loaded with bikes, surfboards and fluids. The front axle doesn't change more than 200 or 300 lbs. While the rear axle will increase 1500 to 1800 lbs depending on the gear loaded in the camper.
What we've done.
Tires: 265/70/17 BFG KO2 E-rated.
Front springs: Replaced the coilover shocks with ICON 2.5" lift
Rear springs: Replaced the rear spring pack completely with Oregon Spring 2" lift.
Rear shocks: ICON stage 5 adjustable
Firestone airbags.
Why:
Tires. I honestly was lazy here an went with the well proven BFG. They are widely available and millions of miles are driven on them every year. I'm not saying they are the best. But certainly I think E-rated tires are a must.
Front shocks/springs: I wanted the truck leveled and lifted just a bit. Nothing to do with the camper. But upgrading the shocks helps with control on mountain roads.
Rear shocks: I went big here. Being able to adjust the shocks based on the load and the terrain matters to me. Rancho RS9000 have similar features. The ICON suspension is just amazing at controlling body roll on a loaded truck and camper in the mountains or in the wind.
Rear springs: With the weight we added we need an "add-a-leaf" at minimum. Our airbags were at 90 psi which is near the max of 100 psi, without an add-a-leaf. Because we're going to remote off-road areas with this truck we wanted the airbags to compliment the leaf springs not to bear the brunt of the abuse.
Airbags: They are great, the adjustability is key. Especially for those that are going to take their campers off. If you're going to be loaded full time, the long-term durability of custom leaf springs is an important consideration. Not cheap, though.
I'd suggest you do your tire research on Tirerack.com to see what the true size of the tires are and get an idea of what is available. We put our 265/70/17's on before the lift and they fit fine. The additional load capacity made a significant improvement to the ride quality to the point that it was obvious how much safer E's just drove in comparison to stock tires.
If you're planning on a fully built up Fleet for use on occasional backcountry and mountain roads I would suggest: E-rated tires, airbags and an additional leaf spring at minimum.
