connect circuit to a cigarette lighter
The LT8640S will operate up to 42V which should protect your circuits against a noisy 12V bus.  It is a voltage regulator after all so its job is to clean up the noise.  The only concern might be protection from load dumps or high voltage transients when inductive loads (fan motors etc) turn off.  You can place a transorb in front of your LT8640S (that is from 12V to gnd).  To protect the transorb, put a fuse in the 12V line to protect your 12V bus in the event the transorb fails shorted.