Controlling power with Isolated DC-DC Converter remote on off vs Relay
However, is it a good idea to skip the relay, and wire up the chip
  directly to the remote on/off of the converter?


I consider this as a contender - the on/off pin isn't isolated from the input end of the Traco circuit so if you need to control this with some isolation I'd consider using an opto-isolator. Please also make sure that when you deactivate the Traco, any back-emf from the solenoid doesn't try to push current back into the output pins to any great extent. You could use a zener diode across the output of the Traco to largely prevent this from happening. Choose a zener voltage that is a couple of volts higher than what the output voltage from the Traco is.