Thanks, guys.

 

I filled a 230 gallon tank up with water, centered over the rear axle in the bed and it drove just fine at 25 MPH. The bump stops or whatever were resting on the axle but all was good. Thanks for the help.

 

For my camper I added air bags which really improved the handling by levelling it out. After having hit the interstate with it I now realize that while a sway bar isn't absolutely required it sure would be a nice addition. I would think a sway bar would be even more critical for a big sloshing water tank. Finnally upgraded brakes is a nice thing to do when planning to haul heavy loads.

With all that you could probably cruise the thing down the interstate at 60MPH. I recently put about a thousand miles on the rig in the pic in my sig on a month long camping excursion holding it wide open at 75MPH the whole time. My problem is the aerodynamics of this thing isn't good and it's a big sail at 75MPH that my 360 push any faster. I suspect a sleeker water tank would allow me to go much faster if that wer the goal.

 

like i mentioned, put the tank up against the front wall of the bed, there will be less leverage on the back of the truck from the load, and some overloads are not a bad idea and are not overly expensive
i carry a 100 gallon fuel tank for refueling tractors and the combine in the fall during harvest, full to the top it only weighs prolly 850 pounds or so, and the suspension on my truck is hardly even squatted, now if i put that tank behind the axle, i can see the rear sag some

that 230 gallon tank, if you put it up toward the front, will have much harder time putting your bumpstops on the axle, and how many leaves do you have in the rear packs, i have 8