rm "$chkdir"/bar/down/to/bar/.filt2
rm "$chkdir"/mid/.filt
-$RSYNC -av --existing --filter='-! */' "$fromdir/" "$chkdir/"
+$RSYNC -av --protocol=28 --existing --include='*/' --exclude='*' "$fromdir/" "$chkdir/"
# Now, try the prior command with --delete-before and some side-specific
# rules.