How do I specify --out in MAVProxy via sim_vehicle.py?

Howdy,

I’m trying to start MAVProxy via sim_vehicle.py. How do I specify the --out option mentioned here:
http://ardupilot.github.io/MAVProxy/html/getting_started/starting.html#out

For context, I’m trying to get it to talk to Mission Planner.

@OXINARF help me solve this issue on gitter. No need to reply.