We see several variations here and the flexibility lends itself to a whole range of variation. I do not think that it would be too hard to rig a primitive root cellar as well when you bring in the shovel to sculpt the earth. Most important though is to put a shed on the end to provide an airlock and separated work space and perhaps a power source that is easily protected..
The whole thing is very much farm boy special. It is clearly best driven into a slope to provide drainage protection. Otherwise we risk over soaked ground causing problems.
The easy scalability is also attractive. htere is no reason that one can put even a few thousand square feet under cover and use the extended growing season to produce substantial output besides jump starting plants to be set out in the garden or field.
With this rig I would start off with straw bales and potatoes simply to produce a healthy soil bed on top of the fresh soils which will not be leached out by rain fall.