Well, as the OP says: the trouble with rationalism:
Being rational concludes I am a total airhead who spews mystical nonsense that can't possibly be so.
Conversely, being mystical concludes that this may be so, and remains a possibility until proven false.
This is what it is to be a mystic. A simple thing. Suspend reason, until reason can no longer be suspended.
At worst, you may, at some future point, feel foolish. And if so, so what?
On the other hand, you may, through the suspension of reason, leave yourself with an attitude that allows the mystery to manifest. Being actually open-minded, unlike all those who claim to be, but are no such thing.
Reality is there to be experienced direct. One may always choose not to do this, and use reason, instead.
Most people do. It is normal. But it is, as you might say advanced, to live life like a crow, inside its day, not just looking-at, but being its life.
The crap life you lead, or a life of wonder, every moment, even after material death.