Travis — FWIW, I use one of those Beachtek boxes with my camera, and the mono audio comes in on ch.1 only.
You can avoid having to use “fill” audio filters after you’ve done your editing if, when you FIRST INGEST your clips, right-click the clips and do Modify -> Audio Channels, then in the “Modify Clip” box that comes up, change Channel Format from Stereo to Mono and then under “Source Channel” select whichever channel has the audio on it (in my case, Left).
This can be done in batch to a group of selected clips.
From then on, only the channel with audio goes to the timeline.
Note that clips already edited to the timeline aren’t affected by this process.
good luck!
Greg Leslie