Actually I paid less then that for the one we have.  It came from a NG Transportation company in central KS somewhere.  Practically new tires all the way around it +1, and 3/4 tank of fuel, too.

I think the steering axle is actually 14500lb.

The truck has a hendrickson.  Unless you extend the frame you are not going to be able to put enough water on it to make it unstable.  At any rate, baffles serve no purpose if the tank is full or empty.  It would look to me like if the tank is not full or empty, there is apparently no hurry.

It will go 62mph with better accelleration then most any truck you could ask for.  I don't know many rural areas that you really need to go any faster then that.

There is a dump truck in this series also.  It would have a longer frame.  Really, in the bigger scheme of things, the truck is such a value that it's not a problem to lengthen the frame.   It should be able to haul 3500 gal with no problem. 

It's not cool enough.  That's the only reason  why everyone doesn't have them.