I have a friend who is teaching me gardening. One of the things I have learned is storing potatoes, carrots onions ect in an old broken freezer or refrigerator. We got one free and put it in the barn. It will hold 3-4 hundred pounds of vegetables and keep them from freezing. You get a electric thermostat and set it to come on at 34 degrees and go off at 38. This operates the light for heat and keeps the vegetables from freezing when it is very cold. Most of the time it does not come on. My mentor has done this for 20 years and only had the light come on last year when we had several weeks of temps in the teens. He stores his stuff all winter in this manner and has not lost anything. Effectively this is a portable root cellar.
Having now done this with an upright fridge I think a chest type freezer will give you more storage area.
Hauled off our old fridge this summer but do have a small freezer that is "kaput". Just took up our sweet potatoes today(29).
I could SO put one under ground! I was going to do 55 gallon trash cans as a root cellar...but a old chest freezer would be the bomb!!! Thanks for the idea!
Before you plant it consider painting it with roofing coat... so it won't rust out quite as bad or as fast....
And digging the hole for the step stool! (that's what takes the most time when we wash the basement windows)