I'll weigh in with my experience with my 2012 Tundra DC with a Hawk. I am running Icon leaf spring packs, Airlift airbags with daystar cradles, and Bilstein 5100 shocks all around, with the spring perch on the middle height setting in the front. Truck sits about as raked as stock except 1.5" lift. I'm now happy with how the truck handles the weight, and when the camper is removed ride is pretty close to stock. I could see custom springs being better loaded, but I run w/o the camper at least half the year and I cant see it doing both well.
I started out with just the Bilstein shocks. The back sagged a lot when I loaded the camper on, and I wasn't happy with sway on twisty roads either. I added the airbags, choosing Airlift because they have a bump stop inside the bag. The way any of the airbags mount limits droop travel, and I found out the hard way that the airlift end caps are plastic and when used as a limit strap the inserts pull out. Airlift did replace the bags for free, but in order to not have it happen again I installed Daystar cradles to disconnect the bottom of the bag and let it droop out. Off road articulation was back to (almost) normal, but the Daystar cradles eat up ~1.5" of uptravel and I was bottoming out on the super stiff Airlift bump stops constantly. The Icon leaf spring pack added just enough height to get me off the bump stops, and seem to articulate better than the stock leafs as well.
I'd really like to know how a 3/4 or 1 ton truck with stock suspension handles the camper, I'm always surprised when I see people adding air bags to these trucks, I guess they also have to be tuned to ride decently unloaded at the expense of load capacity.