My opinion, I don’t think tc13 gives you any value if you have a tc20. If you are depending on the training camps to acquire heroes, you may want to bring that one to a tc20 and run multiple. Some run as many as 4 tc20s but that sacrifices your leveling and it sounds like you have plenty there.
What’s your adventure pack inventory look like? You may want to run tc2. If you really have 1400 in your two tc11s, it would take some time to adjust your recruits.
If you do bring one tc up, I’d eliminate a tc11 and run it at tc2 if you can. You may even want to consider tc1 but that will drain food.
As for farming, I’d refer to the guide linked below. Hope this helps. 