Going thru how exactly this guy will be controlled, one hang up is becoming apparent.  Emergency shut-off!  It's not recommended to rely on a contactor to disconnect power in the event of an emergency, which makes sense.  Seems a lot of people use this switch:

Gigavac Maintenance Switch HBD41AA 1000V 400A Continuous Hermetically Sealed

https://www.evwest.com/catalog/product_info.php?products_id=267

But, looking at the specs (https://evwest.com/support/gigavac-maint.pdf) all the ratings are at 24VDC.  Nothing at the 140+ we'll be running.  A little scary.

Some people talk about a DC circuit breaker located remotely, with a cable operated connection to the driver area.  Seems like there must be a better way.

Found a nice website made by someone involved with the design of the Zilla controllers.  Thinking I'll find some nice info here.  On to reading...

http://cafeelectric.com/Sfaq.php

Not a lot of info on the above site, but after a lot of other reading ti looks like the only legit option is a rated circuit breaker.  The problem is, a new one rated for 150+VDC and 500A is thousands of dollars.  Ebay has a lot of used units, but at the moment, cannot find one reasonably priced (under 300-400).  Saved the search, and will keep my eye out.