Need tank options? Check ag suppliers.
Just tossing this out here. I live in western KS in ag country. We have our bus designed so now it's time to start gathering supplies.
Looking for RV fresh, grey, and black tanks I couldn't come up with things that would fit exactly....and I was dismayed at the prices for what I considered thin walled tanks.
We have built and run several big spray tending rigs that we haul water and fertilizer with for our farming operation so I pulled up their tank catalogs and holy cow what options. These are heavy built outdoor tanks too, built the same as our large tanks we are getting 15+ years out of and they sit outside all year.
I called our parts dealer and have a a 100 gallon fresh tank and a 35 gallon sloped black tank on their way for $220. Of course I'm going to have to drill and fit them myself but to me that is half the fun. They are perfect fits. Most of the tanks can also be ordered with mounting hardware.
This is the company my dealer orders through and you can view what they have on their site . Might be a resource for others as well. Check companies that deal with ag sprayers and tanks I'm sure they can get similar tanks or might have them in stock.
Just an idear.