Sending USBL position to Ardusub

From what I understand, previous versions of Ardusub have have problems with sending position data to the nmearx process running on the vehicle Pi which routes it to the Pixhawk. Is the latest version stable in this respect and does anyone have advice on how to do it? This is just to get the position recorded on the new overlay feature, not for the Position Hold feature.
M USBL system can send data to TCP ports so that would be my preference.