F350 SRW with a Bigfoot 3000 Series Camper - Tires & Sway

A few pictures :)

I had a big response typed, but for some reason it did not post :(

Thanks for all the advice and tips everyone. Feeling a bit reassured and getting more comfortable with the big truck and load! I took the unit for a 1/2 loaded test drive Saturday night and it handled pretty well actually! I even took it on some off-kilter roads and everything handled nice. I also built a 2" 30 psi foam/rubber mat combo to sit under the camper for cab clearance, that may be helping slightly too. The Happijac Turnbuckles make a  nice difference too. I live in a very windy area, so sway is my primary concern, will have to test again when it is windy out, but was happy with things this time around. The truck will indeed primarily be used as a camper unit, so not too worried about unloaded driving. It is also equipped with (I'm assuming) a stock sway bar.

Seems like the consensus is a leaf spring of leaf spring engagement upgrade and perhaps a sway bar. I don't really want to go with 19.5s, already have concerns with clearance and don't want to add to that. Would consider a wider tire though as next upgrade.

Any tips on setting air bags in the meantime? I had them pressured up so the leaf springs were just engaged while loaded and things road nice, including over large bumps. May have been over utilizing though? The truck sits okay without them pressured up, the camper itself has a bit of a lean though. All the pictures I've seen with the 30C10.11 seem to have the lean, must be a design thing..

Your rear limit is more spring and tire/rim ratings than the axel. IIRC the axles in most of the trucks these days are in the 11-12000 lb relm. The 7500-8000 lbs relm on yours is the springs and tires. 
If you have not done the airbags, a redone spring set would be my choice. From using trucks commercially over the last 40 plus years, I've found spring additions to be best. 
On one of my GM SW rigs, I took the 5-1 spring pack, made it a 6-1 with slightly thicker leaves, went from 6400 lbs to 8500 lb rating. It handled loads the same as my later model dually with an 8500 lbs spring rating. If you do not have an above the main spring pack overload, this may be all you need to do to keep the truck level, especially if it is a higher capacity one, ie a 1500-2500 lbs option.
Taller to slightly wider tires would also help. You may/probably will need wider rims. My current 1500 had 8.5" rims, I was able to go from 265-65 tires to a 285-65 and not have too narrow of rim issues. Vs some previous trucks coming with 6.5" rims, going from a 245 to a 265 gave me handling issues vs 7.5" rims and 265 tires. Wider will be a better option here vs taller. Taller will make you effective gear ratio's taller/lower. If you have say 3.73 axle gears now, a 275-70 toa 295-70 will lower this to around a 3.55. A 4.10 to a 3.95. A 315 will knock these down to a 3.42 or 3.73. SOME vehicles this is an issue, others its not so much. You also may start getting into clearance issue with the tires while turning, of bouncing on rough roads, speed bumps etc.

Enjoy the new combo.

Marty

I’d say your setup is ok ish as is, knowing the weight of that camper and the truck you’re using. 
You could upsize the tires to 295s for a rated 4000lbs/each. They should fit albeit a smidge big. 

If keeping the bags, I’d recommend a heavy sway bar, if your truck doesn’t have a factory sway bar and you feel it needs more roll stability. As well, shimming/stable loads to engage lower and or upper overload springs early in the suspension travel helps a lot. 

I don’t have the phobia of airbags that some do and realize their place as a good option depending on the trucks overall use. However if I was setting up a truck solely for hauling the heavy camper, I would be more inclined to just beef up the springs which will be more stable for body roll than having bags support part of the load  

Don’t worry about the trucks overall ability to hold that camper without breaking anything. The lowest rating part of the equation is (aside from administrative weight limitations cooked into the ratings of some vehicles) is the wheels and tires. 
OE rims usually sit around 3500-3600lbs rated. Which you’ll be exceeding by a bit. 
You can get 18” rims rated for 4klbs aftermarket. Which is a decent option if you aren’t comfortable with any weight rating overload on the wheels and don’t want to step up to 19.5s and the cost and limitations of that choice. 
Then tires which your OE size is about the same rating. 
Personal opinion back by decades of using light duty trucks outside their “rated” capacities, there is more than enough factor of safety to haul 4000lbs or slightly more in any 8 lug srw pickup truck made in the last 25 years. 
Lastly tire load letter ratings (C D E F G H) are somewhat misleading. And I believe the F load sizes you’ll find are bigger tires than you want to run, but not rated for more weight than say an E load 129 load index tire like the 295s I mentioned above. 

I'm also not a fan of airbags, their failure can be catastrophic, and they are problematic that they can increase sway. StableLoads and a Helwig Big Wig can do wonders to improve your ride and sway control.   

to me the "best" upgrade would be overloads for the leaf springs and get rid of the air bags.  you can look on line and see different capacity overloads and spring packs for the truck so you can dial in how it will ride with the camper and empty.  I have a 2014 and I think the factory overloads are rated for 450lbs each, you can get them in weights all the way up to 2000lbs.  this will let the truck ride normal when unloaded but kick the factory suspension in when loaded up.