You're pretty much taking for granted that any hypothetical god-candidate would have to interact with humans using some force/particle/field that's pretty much like the ones we already know about.
Yes.
Because our theoretical physics says that the ones we know about
cannot interact with any unknown ones.
Of course, our theoretical physics could be totally wrong. That's my option 4; Your objection here seems to be that my other three options don't include option 4, which is an odd objection to make.
The rest of your post amounts to the claim that idiots might suggest that we are completely wrong, but everything we base on our (wrong) physics just works anyway, by pure luck.
Yes, they probably will. Idiots argue all kinds of crazy shit. Why should anyone listen to them?
Regardless of unknown details of such quantum scale phenomena as wave-function collapse, at the macroscopic scale of individual human beings, or of individual human brains, or even of individual human neurons, the aggregate physics is fully and completely understood, and the possibility of our thoughts being influenced by, or influencing, an unknown "soul", without producing easily detectable traces of that interaction, are zero.
There are plenty of things we don't know. Whether or not souls are a possibility turns out not to be one of those unknowns.
If, in order to save our souls, we need to hypothesise that reality itself doesn't exist (eg we live in a simulation that can be reset by its operator), then we literally know nothing about reality, and can't even have this (or any) conversation, if for no other reason than that the conversation itself is nonexistent.
We can destroy any unpleasant idea (such as the non-existence of souls), by taking the anti-solipsistic approach:
I cannot know that I think, therefore maybe I'm not.
Sadly, doing so also destroys the entire rest of the universe, ourselves included, which seems like an excessive price to pay.