BamBam,
Seeing you have never been outside of Florida, I would suggest a few other things that may be more important.
First thing is have the owner get the truck into a good shop and have the batteries checked out. I can tell you from practical experience that it is a pain to have flat batteries (having two weak batteries soon to be replaced) and carrier a portable generator which I have used a few times more than I want to remember. Nothing is worst than trying to start something cold with weak or dead batteries.
The second thing is buy a couple packages of batteries for you flashlights, buy two flashlights. If you drop, lose or leave your flashlight somewhere, you have an extra. I think (don’t laugh) I have 5 in the truck, two in the tool box, one hanging on a hook, one somewhere in the truck and one I use all the time (the last one is one of those shake to charge light and I left it on a few times when I fell asleep). I also have one of those wal-mart million candle power lights that I have stuff somewhere.
The third thing is get warm clothes now, don’t wait. If you’re thin blooded, you will freeze up here in the north. I am wrapped up right now typing and for the first time since I own the truck I idled over night (sort of) for three hours at a time, with three hours off. I got up at 3 in the morning to find that the sleeper/cab was 95 degrees and woke up at 6 to find that the temp dropped to 55 with the temp outside at 12 degrees. I do not have a thermostat at this time, I also have a heater valve that I messed up and it is stuck open. I got an army (actual military) quilt last year; it is amazingly warm and a wool blanket for my feet to help keep them warmer and a Swedish civil defense coat (heavy wool/canvas coat) that I also throw over the quilt when the temps drop to zero. I don’t mind this but I would rather have another source of heat other than my engine.
The fourth thing actually goes back to the first thing, getting an inverter. The thing is that inverters use power and you sometimes need to keep checking the batteries to make sure you don’t flatten them. I would just get one of those cheap $29 400w inverter, you can’t run all kinds of things off of them because they are not really meant to be a replacement to the wall plug but they will keep your computer charged up. If you plan on getting one of those coffee makers, I would carefully selecting one and remember that the cheap inverter will not power most of them. The one I got draws 1000 watts just like a microwave. I know that they make 12 volt coffee makers and you will have to run the truck for them (or at least I do) .