This is what I did with a similar crazy who showed up for the initial visit and stayed four hours:
I told her she could build a small wood paddock within an existing paddock that met both of our specifications. She would supply materials and labour.
She would supply her own feed, as she wanted something I didn’t offer and had no interest in carrying.
I would charge for every weird incidental need, pony was being rehabbed from…Munchausen by Proxy.
The base board rate I literally just doubled my standard rate. She was really annoying and crazy, but also both she and the PONY were very high maintenance and had been asked to leave the barn they were currently at that could “no longer meet her needs”.
I sent her an email laying all of this out.
She responded that such and such farm was only going to charge her x. I said, that’s fantastic, you should definitely go there, and I never heard from her again.
I figured if she came, I would get a new paddock out of it, at least, and money. But I knew it had to be enough money to make up for the crazy OR deter her completely.