Great question, I like where you’re headed with this solution. You’re asking the right questions with regards to system size and viability.
An independently powered refrigeration system will take pressure off the existing static solar arrays and any mobile solar systems that are deployed to the Cape, so I believe that something in this direction would definitely be useful.
One thing I’d suggest you consider is the mobility of a 20ft container. Seeing as your plan involves modifications, is there potential to halve the 20ft container and create two, smaller units that could be potentially mobile, either into the field, or between ranger stations/homsteads?
An important thing to remember about the Cape is that many homsteads and stations are not occupied year-round, and rarely for the entirety of a dry season. So any assets that have to remain in place have longer ROI’s, and need to be extra resilient to weather and to long periods of non-use. Systems with mobility can be taken on and off country, but carry with them other design constraints that come with travel on rough roads.
I hope this helps you refine your direction,