Telemetry of a serial sensor

Hello Team,

I am trying to telemeter ASCII serial data back from a turner designs C-Flour digital Fluorometer installed on an autonomous boat with a Pixhawk 2.4.8 running Ardurover 4.0

Ideally I would like to write to an SD card (either on the pixhawk - can I do this? or on a companion computer - Raspberry pi?) and simultaneously telemeter the data back to mission planner using an RFD900X.

Is it possible to plug the fluorometer into Serial 4/5 port on the pixhawk and telemeter the data that way? Or will I need to modify the pixhawk firmware and write custom scripts etc?