How can I pre-register my study of little importance? I am writing an undergraduate dissertation on behavioural economics. I am looking to run an experiment. As nobody apart from my course convenor will read my paper, the stakes are not particularly high. Nonetheless, I want to i) follow best practices and ii) prove to the examiner that I have not done any p-hacking or HARKing, in the hope that I will get a higher mark.

I am therefore looking for some way to pre-register my study and hypotheses, or otherwise prove that I did not amend my hypotheses. This previous question on Academia.SE did not have a good answer. I have also thought of writing down my hypotheses in a public blockchain to have a proof of existence, but this seems far too esoteric and I doubt my examiner will be impressed.
If you have the time for it, you could blog the entire process from initial idea through the final writing of the paper. A public blog might not be the same as a, audit but the public nature of it would provide assurance. A research notebook open to the public, so to speak.

But I suggest this since a blog of a research "journey", including all attempts and all setbacks would be, perhaps, useful for others starting out in research. The fact that, you say, it isn't very deep might be an advantage, making it more accessible to readers. 

It might even make you a better writer; valuable in itself. 

There are a lot of blogging platforms, of course. And I realize this isn't exactly what you were asking for.