Doug Wagner of Keystone is making bodies for various types of tankers. Check out his site and you will also find wheels and lug nuts.
Prices are a 3 pot cement tank is $60
a 2 pot cement tank is $40
a single pot pup trailer tank is $30
Chemical ribbed tank is $80
And oval fuel tankers are 16.5” $68 22” $88 Straight truck fuel tank 11” is $58 all plus shipping to your zip code
Also Jamie Rahmoeller (moluminum) and he is on Facebook he makes an accessory kit that goes with my trailers. You will have to get ahold him to buy them he sells resin tires n wheels, dome lids, all the valves you will need, front n rear fenders, axel assembly, resin wheels, chez lights for trailer, etc. also you have to scratch build the frame using evergreen or Plastruct or kit bashing.