Reminds Me of a thing called a Zeer pot
I learned from Steve spence of green trust (site defunct )
to bad because most his stuff was mechanical , and interesting homemade solor power etc.
but is suppose to be good in hot climates like Africa with no electristy
I also agree with Hillbilly Hort 2 feet deep could be good (I make a pit for seeds cold straticfy )
May niot be the best they aint big . (zeer pots)
It is clay Pottery With Sand that is wet in the bottom
the hole is bigger but the pot is held off the ground with a stand (or rocks piled on edges)
Sand is also coated around the sides of the pot
The air flows around the pot, and from under the pot keeps stuff cool. (suppose to 40 F)
I think camping or something that could be a good trick
Not sure if you could use something bigger Just reminded me of it
2 feet down sounds good I guess
Interesting JC (edit Thank you) I was always against storing things in plastic,
I guess Potatoes do not make a lot of ethylene though
I know not to store by apples though the ethylene will ripen them to fast.