In Plans/Advanced roadmap how to get the collapsed Project to show an overall timeline

I love Plans/Advanced roadmap. We have quite a lot of JIRA Projects - when they are expanded I can see the timeline bars for each epic. I’d love to, when they are collapsed, see the overall timeline (e.g. starting at the start of the first epic and going to the end of the last epic) for each Project. Is this possible?

It looks like I could package all my epics into ‘initiatives’ or some higher level hierarchy and this would work but it seems unnecessary when the Project wrapper already fulfills this function?

Any thought/help hugely appreciated.