Yup, and as soon as they hear about the land purchase and your threat they can/will change the zoning.
If you try to protest they will let the neighbors know that you posted that you are going to put in a stinky pig operation out of spite. (lawyers do know about the internet)Do you think the neighbors are going to roll over for that?
Sounds to me like a pizzin contest and they likely have the bigger pump.

You had/have a special variance which is not permanent. They decide to call it back (shrug - life's a bitch and then you die)
Take your money and buy land suited for storing your equipment that is not right on the main drag, sell this land for a profit if you need the cash, and stop tilting at windmills.

Actually, they just handed you the zoning keys to a new set of condos or duplexes to rent out that will earn you more money in your life than keeping it a storage yard. I wish they would do that to me.

GL