Hi there, @Jennifer_Yosowitz 
I’ve checked your widget and see that you’ve already used the Host filter as a workaround. Could you please let me know if the Host filter covers your use case for now?
We also have a Wishlist request for the Custom filters option. You can upvote it here - Need To Add Custom Filters
As for the time-zone display, we also have this idea on the Wishlist. Feel free to share your vote here 
- Simplify time zones