I'm a vegan. I have not yet considered fully whether or not the beliefs behind it, and this specific course of action based upon those beliefs, are rational.
It seems to me that it would be against my personal morals to assume that I have the right to enslave or take effort from a creature whose intelligence I cannot, at present, measure or determine. I'm not sure if intelligence should be the basis for this decision.
From what I've seen and read of the meat industry, it does seem that this specific industry and way of doing things is one I wish to avoid partaking in as much as possible.
I'd very much like to hear from people who have considered this issue rationally and indepth, as it is one that is very difficult, for me at least, to discuss without bias.
To add; for me, health is a lower priority to the concerns mentioned above (to a certain extent; I'm okay with operating at less than optimum health, not okay with actually dying), though I do aim for health within the constraints decided on by higher-priority choices.
Not sure if I can articulate this well, but I wonder if you're focusing too much on ghosts while evaluating this thought experiment? Couldn't option three be rephrased as; "There may be something in this environment which can hurt me. All defence systems on!", without the fear being specifically of ghosts? In other words, couldn't your subconscious be picturing scary thing, and not, specifically, ghost?