I’m not sure that Root Cellars are a ‘thing’ in hot climates.
The space I want to use for ours is under the house, in the field stone basement which stays about 50 degrees year round.
I would say it’s 10 feet under the first floor of the house. The basement and the separate room I want to use, has field stone walls, built with local rock back in 1900. I’m 100% certain it was built as a Root Cellar when the house was first built. BUT - getting all of his ‘Boy Stuff’ out is where the problem lies!
Our basement is very, ‘Silence of the Lambs’ so I want MUCH brighter lighting down there, LOL!
I found this for you for starters:
https://journeywithjill.net/gardening/2016/07/04/store-potatoes-hot-humid-climate/
Basements in old farmhouses are the worst. Crumbling stone or nitre on the walls...coal cinders on the dirt floor. You knew they kept roots and canning down there...you wondered if they kept their insane aunt down there as well! Brrr!