Re: Fun with MF images, part 2: What are you shooting with that MF back?
Ideas from DSLR world, but same risks apply. If really cold, bring plastic bag outside with you when you shoot. Before getting back into truck, put camera in cold bag first and make sure bag placed in area that will allow contents to slowly warm (e.g. not in front of heating vent, sunlit window, etc). Cold camera with cold air inside and cold plastic enclosing it.
Idea is that condensation upon sudden temp shift forms on outside surface of cold bag, not on camera. Situation is reversed going from really cold AC'd car/building to warm & humid (South Florida anyone?).
Winter adds the extra threat of any condensation that does form freezing if an effected camera suddenly goes back into cold environment.
Other option if and out of truck often would be a food cooler - older and uglier the better. First time out bring cooler out and leave open during shoot. Before you get back inside, put camera (sans battery to keep it alive longer) in cooler, close, etc.
Leave truck: take out cooler, remove camera (leave open during shoot), insert battery, shoot and reverse. Keep batteries warm in coat, etc (or use battery pack in coat and cable) and let acclimatize for a second (just in case any condensation forms on shell) outside before inserting.
Insulated outside air in cooler allows camera to warm very slowly when back in truck - lowering odds of condensation if you wake repeated trips in/out of warm car. When home, bring in closed cooler and just let it sit and slowly warm up. Many arctic shooters leave gear outside in Pelican's (sans batteries) until they need to come in to avoid a lot of temp shifts. Of course theft is less of an issue...
Could use same technique if going from AC'd car in hot/humid area to AC'd offices and back a lot. Adding a dehumidifying gel pack in cooler would cut back odds of any moisture forming inside even further.
On top of that no one would ever guess that old ratty cooler in your truck held $$$$ of gear.
101 ways to do it, but the idea is to allow the cold/warm surface of the camera/lens to slowly adjust to sudden temp/humidity changes and to ideally keep such shifts to the minimum feasible.