Warren,  A conex is an excellent storage unit, but one thing you
should be aware of is humidity control.  Even in moderate temperatures,
condensation can be a problem.  As the outside of the container heats
up during the day, the cooler air inside will condense any moisture
onto the ceiling, which will eventually evaporate and start the cycle
over again.

My recommendation is to install a humistat on the control switch on
your ventilation fan to evacuate any moist air that might accumulate
in the container.  Other than that, a conex makes a great pest proof
storage system.

Tom Barrett