They should offer property tax breaks for the lifetime of the current owner. They sell or move off - lose the tax break. THAT will work.
Most of our southwest border is already federal property—except Texas.
They may have to be reminded that they are still one of the 57 states ... the stubborn cusses.
Yeah, that might be a good inducement: like a nonconforming use that is amortised out or lost when abandoned.
I would volunteer to tell their land commissioner that they can’t depend on that income for a few years.