I didn't walk into retirement myself, but was dragged, kicking and screaming!
Your plan sounds enviable Monty. Especially the 18-acres part! Wow, a mountain retreat!

I had 10-foot ceilings in a previous home and that was luxurious. I wouldn't build anything less. In fact, for a studio, I'd just build it as tall as budget/codes/restrictions allowed. But I'm a dreamer!
I'm fortunate to have a very large living room here. But with only 8-foot ceilings, it's very limiting.

What I DO have is a large-ish patio in the backyard with an "unlimited" ceiling that goes straight up to heaven.
So my hope is to set up an outdoor studio and use scrims and reflectors to harness the Tennessee sun.

I learned to do some pretty decent product shots back when I lived in California just using my front patio. But the sun out there was a more consistent light source and rain was almost non-existent some months of the year. Still, I'm fairly optimistic.

I wish you much luck and joy in your pursuit!