A >12oz hammer.
A sacrificial kingpin nut.
A hard surface you can hammer on.
Thread the sacrificial kingpin nut nylock first onto the threads. Tighten until the nut sits 1-2mm higher than the top of the kingpin. Put the baseplate on a hard surface, kingpin facing up. Safety squints. Hold the baseplate and hit the nut firmly and hard repeatedly with the hammer. It may take a minute or two of swinging.
If you forgo the sacrificial nut, the threads will become peened, and you'll have to file them down to fully remove the kingpin. Good luck!
Here's my hollow collection (nevermind the DLX pins, oops)