Here are our experiences...
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a)
A used reefer has odors, absorbed moisture, and weighs a "!ton!" more than an empty box.
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b)
Our earlier version of our ExpeditionVehicle had an enormous 24L x 8W x 8H reefer.
Our Cummins 8.3 through the Allison 3060 struggled with that amount of mass.
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You might theorize the six inches (6") of factory insulation simplified temperature control, but heating that cubic space was nearly impossible.
Something didn't compute.
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We dumped the whole shooting match, started over.
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2003, for our ExpeditionVehicle next version, we switched to a 12L x 7W x 7H dry box.
We insulated with:
* adhesive-back acoustic against the inside of the wall and ceiling, a gap, then
* one-inch pink-board, another air-gap, then
* two-inch foil-side poly.
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The floor has one-inch pink-board covered by half-inch marine plywood, painted on all surfaces to seal.
Two decades full-time live-aboard, that pink-board shows zero indication of crushing or crumbling.
Pretty much good as new.
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Our windows are 3010 (three feet wide by a foot tall) dual-pane sliders designed for a stand-still house.
We mounted these at our eye-level standing inside, about eight feet above pavement.
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For heat, we use one Wave 3 catalytic heater set on 'LOW'.
We always open two windows on opposite walls.
Escaping warm air carries humidity and odors.
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We rarely use the heater above about 40°f.
However, the windows are always open at least a half-inch.
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Our insulation weighs practically nothing.
The primary advantage to our system is the air-gaps, the dead-air trapped between the layers.
Plus... these materials are engineered to not absorb moisture.
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c)
Our latest conversion is a 40' semi-trailer.
We acquired it as a reefer, but the odors were overwhelming, the wood rotting, the humidity gassing gagging.
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Initial Stage:
We hired some local goofballs living in a warehouse-pallet hovel covered with blue plastic tarps.
In about a month, that wonky crew stripped the interior to bare aluminum.
It was a scummy disgusting mess.
They earned their ten fedbux an hour.
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Simultaneously, we lowered the roof by 18"/.5m.
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With the success of our air-gap system, we duplicated the insulation concept of our ExpeditionVehicle.
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An aside:
One yuge problem maintaining temperature in a factory RecreateVehicle:
* big picture windows so you can sit in and see out.
Those big windows are impossible to keep from weeping, because of the temperature difference inside-to-outside.
Constant condensation.
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With your potential build on an ex-military, might you head down narrow trails?
Small windows are a small target for branches and jealous by-standers.
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Although your vehicle has the GVWR, any reduction in mass equals better fuel mileage, better handling and acceleration, and longer tread-life.
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"But but but LM!, how do you live in such a tiny space!"
We do not live in our rig.
We live out of it.
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Our introduction with plenty of portraits, plus our reasons for our decisions:
https://vanlivingforum.com/threads/e...8/#post-576110