Attach a peltier to the HD. Get a thermister, and rig up a circuit that will send only enough power to the peltier to heat it to a set temperature.. just above freezing, for instance. The circuit can disable the peltier after the thermister reads above a certain temp.
If you attach the peltier facing the other direction.. you can cool the HD (for the Arizonians amongst us). As long as the temperature difference is not that great from room temp, condensation shouldn't be a problem. If anything, you can just insulate the whole thing in styrofoam.. that should also help with shock absorption.