I had a rusty 25-year black iron tank with inaccessible areas. I tried to have it power-coated but could not get the residual vapors low enough for the job. I replaced it with aluminium one built by a local shop. An advantage was that I could design it to get the maximum capacity for the space. I had them put in a return port in case I eventually switched to diesel. One piece of advice was to minimize contact with wet wood. So I fiberglassed the platform and had it sit on strand-offs.