There was a kit for the brake van used in the earlier weed killing train. It was an ex MR van the IWR used if your doing SR.
The IWR water tanks were very unusuall in profile!!! And had several chassis over the years.
For the odd shaped one, please do not laugh but due to the wierd profile, the only think close was a sweetex sweetner dispenser which I cut into sections!!!!! It is slighty tapered too so I had to sort that. But by cutting ito into quarters for the top, then the bottom tapered bit was sectioned into quarters again. The chassis I used an IWR chassis from Smallbrook Studios I think. For the private owner Royal daylight wagons on the Island I modified a mainland tank wagon. I think the tank wagons and Isle of Wight cranes have taken the longest and are the hardest to build. The next hardest are the SECR composites!!!