Roadside flares?

No they don't, when I worked a road services many years ago I had people try and run them over

 

There are never enough cops in construction zones.

 

Besides, in an emergency situation you can light the truck with a flare to stay warm.

Being in Montana, I carry flares in every vehicle. Good for starting fires when the matches are wet. Screw rubbing sticks together.

 

You can order flares from awdirect.com or try your local volunteer fire department. I used to volunteer and would get my flares from the department, still do. If you explain why you want them they should be willing to part with a dozen or so. Get a plastic tube to keep them in so they stay dry, plus they have a habit of leaking if they do get damp, this will protect the inside of your cab.

 

Or they tape them to the back of the trailer