Well, the temp range normally indicates lithium, but I'm thinking that the cabin rarely gets that cold (or that hot) so it will only be outside for short periods of time. To me, that means alkaline will work just fine, especially if the batteries are 'insulated'. Needs to be durable against drops as well. Those two criteria add up to a 'plastic' or composite bodied flashlight. You won't fret over scratches and the light won't make horrible noises when it drops off the top of the trailer, hitting several things on the way down.
All that said, there are a few good options for you, IMHO. Streamlight 3C 10 LED would have awesome runtime and great flood beam. Throw won't be very good though but I don't know if you need that. Another one would be the UK 4AA's, both Xenon and eLED. The Xenon (incandescent) will have good throw, great brightness, decent runtime, but a bulb that has the ability to break (which LEDs really don't do). The eLED won't have the throw of the Xenon or quite as much flood as the SL 3C 10LED, but it will have FAR longer REGULATED runtime, can run on AA lithiums, and will be virtually indestructible. I don't know if the Xenon 4AA can handle lithiums or not, but it might. Both of these two are easily pocketible. You could even buy both for under 50 total!
Just some ideas. There are plenty of options out there. I really don't think a 123A light is necessary for what you are asking...
Mark