Solder will be fine, heat will not be a problem, but with you needing to get a bolt to that temp(300C or thereabouts) any close fitting plastic will melt, this is with it off the car and opened up though, plus you will need a beefy iron to get enough heat, they don't get any hotter but can solder things thicker as they can keep up with heat needed.
As said a no no on the car really.
tabetha