Jumpers will never replace old metal coat hangers.
For my first few jalopies, I always had a few coat hangers in the trunk. Tore up several exhaust on snow and ice banks growing up in the great white north.
And a soup can or two. 
Well yeah.... that was for
after you got home.
There was also some cheapo epoxy concoction you mixed up and gommed all around the hillbilly repair to try and keep it glued together and air tight which worked pretty well for a few weeks.

And back when cars had straight vents, I learned to drive with all the windows up and the front vents open, which sort of pressurized the compartment so you didn't carbon monoxide yourself to sleep/death with exhaust leaks under the car.
Ahhh, the good old days.