I don't think you appreciate just how dangerous these things are, but at least you are thinking about fuses now.
When one cell blows while it is wired in parallel, that will act as a short circuit to the other cells. This will create a cascade failure which then sends the entire pack up in flames.
Once that occurs huge molten metal chunks of Lithium will go flying into the air inside of the cabin of your vehicle, into your head or neck or chest.
Setting the upholstery on fire.
Ontop of that it produces hydrogen gas once venting:
This is what happens when you heat a tiny little CR2032 Lithium battery:
And this is a battery
PACK of them:
Seeing as you are going to continue to use that battery technology, which when fails reaches a temperature of 1100F, at least take
preventative measures.
#1 Wrap each individual cell in fiberglass fire blanket, cut it up into strips each the length of the battery and wrap them, all of them, individually! This will prevent the heat coming from one failed cell to ignite the rest of the pack.
As it is now all you will need is just 1 of the cells to go bad for everything to go up in flames.
#2 Buy a metal ammo can, install the batteries once they are insulated inside of this ammo can. Then drill a 4mm sized hole into the bottom of the ammo can and another one into the bottom of your car and using some rubber hose that you can get from car parts stores, vent it to the outside of your car. This is to ensure that any red hot gases which will come from the batteries aren't going to be going into your lungs.
#3 Then, buy an ABC Fire Extinguisher and properly mount it to the floor of your car, that way once this battery pack does ignite you can at least prevent the rest of the car going up in flames.
And. Good luck.