I would use a solid state relay, but the output is using a DC pulse current that can max out at +/-15A. I though solid states are used with AC outputs?

Any SCR or triac SSR will stay latched if its switching steady DC current. A pulse would end at some point and commutate the output device.

Telecoms sometimes use a bidirectional MOSFET SSR/optocoupler in the usual 6-DIL package. They aren't rated for continuous current at 15A - but if the pulse is very short, it may fall within the surge rating specified on the datasheet.

There are probably higher power versions - I just don't know about them.

 

A $2.50 Hasco CS212-DC12 will actually operate from 8.4V to 30V and will basically "survive" 36 volts and is polarity insensitive..
http://www.onlinecomponents.com/hasco-components-cs212dc12.html?p=11506520

 

A $2.50 Hasco CS212-DC12 will actually operate from 8.4V to 30V and will basically "survive" 36 volts and is polarity insensitive..
http://www.onlinecomponents.com/hasco-components-cs212dc12.html?p=11506520

This looks perfect! Thanks.