Tanks are sold b y size, so you don't have to be camper specific. Measure the tank and either go to a parts store or get it on line. They are really not that expensive and they can be shipped cheap since they are lightweight, although bulky. And you will need to replace the valves.
Just another thought, I have seen some long-term/permanent RVers who have hooked up directly to sewer. Some have bypassed or removed the tank altogether. I am not sure if there are any downside to this, but I can't imagine this would be a problem if you do not intend to drydock.
Goo luck to you.