Hello Ryan!
Welcome to the forums! 
Let me return to your first question:
Looks like you found Liz's posts on truncation. I approach this decision a little differently, so perhaps you would find my post on DADA2 trimming, truncation, and merging as a helpful comparison.
I always truncate data when running dada2!
When working with a new batch of samples or new cohort, I often run DADA2 multiple times to see what settings cause the most reads to join. Like, half a dozen times! 
This is called 'parameter sweeping' or 'guess and check'! 
You can decide what to run next!
what I recommend:
I would try shorter values for --p-trunc-len-ras R2 looks pretty rough.
220 might be two short but it would cause a lot more reads to pass filter without resorting to raising max-ee parameter to 5. Depends on how this goes, either trunc shorter to remove more of the low quality R2, or trunc longer to get more overlap and thus more merges.