Wow, great photos from your trip. Maybe post a link over at bikepacking.net's forums?
Comment should go into the 'note' field on the GPS. I need to double check this, will do.
You are right that all saved tracks come out red on the GPS. I believe this is one little piece of code I have intended to write since adding per-track coloring a while back, but it keeps eluding me. Will put it on the top of the list.
On combining multiple TF tracks, funny you should ask, I just added this yesterday -- long overdue really. However, it will not get you around the 20 track limit, unfortunately. Even if they are in the same file they'll still eat up a track each. One thing you can do is upload to the active log -- the active log can have as many different tracks as you want, but is limited to 10k points. Then, of course, you'll overwrite it as you go, so you'll have to be careful.
Thanks for the feedback/questions. Love seeing TF used for bikepacking new routes!