Avoid exshipping containers like the plague!
They will sweat condsation and anything that touches the sides will suffer.
Go for the internal units in a larger building, the temperature variations will be less.
I own a shipping container workshop. My first winter in it was last year.... jeez it was bad. Previously i had a different container as a store, then bought another for a workshop. When it started to go cold, the roof condensated and dripped on the machines... i hadnt been there for a week and what a terrible sight!! I put waterproof covers on, still went rusty, waxed them, slowed it, but still rusty! Although hot wax is one to remember....
In the end i insulated the roof and got a dehumidifier, now no problem. The dehumidifiers dont work below about 10 degrees for a refrigerant based one and 5ish for a dessicant one, but the insulation holds it off. Mind you, my roof could be slowly degrading and i wont know about it