Thanks everyone for the replies. I didn't mean to get stuck on the terminology. I think it's fine to grow your orchid in whatever medium suits best for your growing conditions and culture. I grow many of my epiphytes in pure leca or pure water. Regardless of the "medium" in nature.
My way of mimicking this "rock and crack growth" was to hang it loosely on the mount and wrap a bit of sphag around the rhizome/roots with fishing line. I just have a difficult time understanding if this thing wants to be dry or moist - which seems to want both at once. haha...
That's why I was curious if anyone had done something similar or devised a clever way to grow them well mounted.
The main difficulty has been the long (5") rhizome. I was debating to throw this thing in the yard and let it snake on the rock/sand/desert that is soCal.
I think I will just keep going at it the way I ahve been for now. If it fails... ah well.
I've been on inselbergs in eastern Minas Gerais. I never saw this plant. Given the elevation data it will be warm to hot in winter during the daytime with substantial cooling at night. It will get dew most nights but not much rain. It probably grows running along thin mats of decaying leaf matter that accumulates along cracks or at the bases of other plants. These almost never dry out. In summer it will be constantly very wet, very humid and always extremely hot.
Again, I'm not familiar with it, but I doubt you could keep it watered enough on a mount without an automatic watering system.
__________________ May the bridges I've burned light my way.
Given that it is at least somewhat terrestrial, I'd put the mount into a pot with some sphagnum. Try to get the moisture content higher around the roots but still keeping it airy.