none rod truck tool box help

hey guys
after x-mas Im going to buy a tool box for my truck, In my line of work I somtimes have to carry a few gallons of a gas leak detection fluid. I want to keep them in the tool box in the bed to do this in the winter I need to keep them above freezing I dont plan on keepping the fluid in the box 24/7 I just need to keep it warm wile im driving to and from the job site up to 4 hours away any ideas

I have nothing unless you put a 12V to 110 converter on your truck. If you do that you could toss a heating pad in the bottom of it. It would not keep it hot but should stay above freezing. The old water pipe wraps. Those are getting hard to find due to house fire problems. A guy that I use to hang around his shop when I was a kid had these heated magnets. I have never seen another one so I have no idea where he got them. He kept his paint on a metal table. In the winter time he would toss one or two on table with the paint around it and it would heat the table up enough that the paint would make it through the winter without fear of freezing. If I remeber right they where like a 6 or 8" square box. I have been wanting one myself so if anyone knows what I'm talking about let me know the name or where I can get one.

http://fivestarmanufacturing.com/Kat_s

The Handi-Heat Magnum provides 300°F to 400°F heat for heating or thawing engine blocks, oil pans and transmissions on trucks, tractors and other large vehicles. U.S.A

http://www.amazon.com/Kats-1160-Magnum-Handi-Heat-Magnetic/dp/B000I8YOR4/ref=pd_bxgy_auto_text_c

http://www.amazon.com/Kats-1153-Handi-Heat-Magnetic-Heater/dp/B000BOABS6

http://www.amazon.com/Kats-22200-Watt-Battery-Thermal/dp/B000I8XD9E/ref=pd_bxgy_auto_text_b

lol that's them. The one he has was pretty old and didn't look the same but that's what I need.