Currently (that I'm aware of), there is no way to promote your channel while you're offline - unless of course it's through another site (e.g. TikTok, YouTube, etc).
So, I thought of a solution. How about adding an 'Offline Recommendations' tab underneath the 'Recommended Channels' tab list - this would replace the previous 'Friends' tab.

How it works:
It'll work similarly to the current Recommended Channels, except only offline streamers. That way, it gives creators more reach with less effort! Of course, it should only recommend streamers that have been live within the past XX amount of days to prevent any inactive channels from clogging up their recommended page. (14 days or less maybe? - up for debate)

Pros
- Offline Recommended will help grow channels by promoting them offline!
- Will increase usage in Channel Trailers; giving people a reason to use them!

Cons
- Likely could be used against creators in offline follow bot attacks

Let me know what you think about this, I really think this one could benefit not only creators but viewers of Twitch by giving them more content creators to watch and support!