As one answer, I do remember an advice from years ago:

1. Write down the ideas and some of implementation details in a book.

2. Submit it to Lulu or other self-publishing site, order a few copies to yourself, but don't open some of them.

3. If the case comes to court, you can provide the package with the postal stamp on it, and the content of the book shows that you were aware of the idea before the patent-troll filed for the patent.

One issue with this is that the court might reject the package with the postal stamp, so it might be useful if you have a copy with a notary signature or like that.

Please let me know if you see any flaw with this approach or share if you have a better one.