The LRWAN code typically provided a PRINTF() function which outputs to a console or debug channel.
My approach is to add as much instrumentation and telemetry as possible so I can observe and understand what's happening in the system real-time, and from both ends. You'll likely want to add some basic packet dumping functionality, and/or structure what's sent to be printable, or with sequence numbers, etc, so you can see it working, or if there is data loss, etc.
If you plan on pushing some known format data across the data-link, you could perhaps decode or track that, reporting on message numbers, integrity checking, etc.
As the Ping-Pong can be some what erratic or meta-stable, I would tend to fork that into receiver and transmitter modes, for range testing perhaps a periodic position report from a GPS/GNSS receiver, logging that, and mapping as one node is moved around.
