Smart idea?

I Have thought about extinguishers in my work van as an industrial painter, i often use all the nasty flammable paints available to us humans but i also think about the accesability of the extinguisher too. in your example you have the extinguiser in the boot/trunk of your vehicle, the boot/trunk is likely where your fire may be,(with Li-Ion batts in the boot etc) which requires you to have the extinguisher at an alternative location OTHER than the expected fire area....Dont get me wrong your a step ahead than alot of us, especially in your New Love of your life(car)
I have done a few training courses on extinguishers and they do teach us to keep the extinguisher in an alternative location, for example.... you dont have the kitchen extinguisher right next to the oven you may have it in the kitchen entry etc...
Also...... you should start a CONTROLLED fire in an open area and test both C02 and Dry powder extinguishers against some basic fires and test there effectivness! you need to know the range and effectiveness of the extinguisher you are Using other wise you might put yourself at risk by fighting a fire that is impracticle especially with an extinguisher that you have bolted up but have never used before.... before i finish this convo sounding like your mother.... dont forget you can Cool your Beer with A CO2 extinguisher , and it converts a warm beer to an ice cold beer,
Anyways Im Out ! RYDorDIE!
Stay Safe