Is this what you are looking for?

So, you are correct about the entire TOC being run in, or not. But here's how it works: when the tag names are sequential, i.e. 2 or more Trails tags in a row they run in. If the tag names change, i.e., 1 Main Heading followed by 1 Trails, they break on to new lines. So, I see two options:
- Make the whole thing run-in and manually adjust after the final update OR
- Create two tags for the Main Heading. For example Main Heading and Main Heading1. Be sure Main Heading1 is based on Main Heading and has the exact same definition. (This means if you ever update Main Heading, Main Heading1 will update simultaneously.
- Alternate the tagging for the consecutive heads (1 is Main Heading, the next is Main Heading1, then Main Heading, etc.) If they aren't consecutive (i.e., Evergreen and Steamboat), they can just be Main Headings.



- Now back the the TOC dialog box. Map both Main Headings to the same TOC style. Turn Run-in on.


- Then map the Trails tag to the TrailsTOC style and add your em dash between the entry and the number.

- Then update!

~Barb
P.S. you do have my favorite Evergreen and Steamboat trails in there somewhere, right? 