You could try emailing the authors of some related research papers or professors at your next university. That's basically how I found the advisor for my undergraduate thesis. I had an idea, looked through the CS department's website to find the ML researcher whose work was most similar, then emailed him a proposal.
You will probably have to make an effort to differentiate yourself from crackpots and demonstrate pre-existing knowledge of the field. In my case I had to answer a number of questions of the form "I think you may not be aware of XYZ, which is quite similar to your idea." with "The paper on XYZ inspired my idea, but I'm trying something different."
A targeted venue that pre-selects for researchers willing to spend their time on mentoring others (who are not officially their students) could help, but it would still have to deal with the crackpot problem.
You will probably have to make an effort to differentiate yourself from crackpots and demonstrate pre-existing knowledge of the field. In my case I had to answer a number of questions of the form "I think you may not be aware of XYZ, which is quite similar to your idea." with "The paper on XYZ inspired my idea, but I'm trying something different."
A targeted venue that pre-selects for researchers willing to spend their time on mentoring others (who are not officially their students) could help, but it would still have to deal with the crackpot problem.