Passing Serial data in Serial4/5 port thru MavLink?

I know I am a bit over my head here but just wanted to get some input and some direction from those who will know more about this than I. I have a Pixhawk, it has Serial4/5 port open and I was curious if it was possible to send data through this serial port and pass it through the siK radio’s? The data is from a sonar/fish finder that has a 5v TTL signal, that I would convert down to 3.3v with a logic level converter, like this one:

The NMEA 0183 output from the sonar is at 4800baud (from what I have read) and the following sentences are outputted:
DPT - depth
MTW - water temperature
GLL - Lat/Lon Position
GGA - GPS Fix Data
RMC - Recommended Minimum Specific GNSS Data
VTG - Course Over Ground and Ground Speed
ZDA - Time and Date

Now could this serial data be be fed through the Serial 4 port and sent through the siK radio? I have other ways of trying to send this data, but this would be the cleanest and most energy efficient way to do this.

I’m trying almost something similar: data collected through an arduino-nano on board to send serially to pixhawk connected to serial 4/5. The pixhawk mast then operate as a repeater and to send the data to the GCS where I mast be able to see them. I have already done the arduino part of the application however I can not yet communicate (through MAVLINK???) with the pixhawk. Any help welcome …

The sik radios simply act as a serial line. They accept serial input, transmit via radio, then receive and convert back to serial. So you can, if you wish, just connect your sonar data to the sik transmitter directly and it will come out serial at the downlink side.

Now if you want to take serial in data from the sonar going to a Pixhawk serial port, then reroute it to an outgoing serial port that is a different problem.