Regulating voltage with low headroom
how  about using a 10amp or 20amp stud-mounted rectifier, in series, to provide the high current.

Use an LDO to provide the 0.2 amps.

And, if there is spike/trash on the +13, use 1milliHenry and 1,000uF low-pass filter, the inductor in series with VDD, and the cap shunting to ground. Place a 1 ohm resistor in Parallel with the inductor, to dampen ringing. (use Rdampen = sqrt( L / C) to compute.