Extending Turn Length of Vanilla scenarios?

[Rosseau]

Is there a way to do this as part of modifying an existing scenario?

I see the "start date and round length" options in the dashboard...can one elaborate?

I'm getting along well with the Simple Editor, and it's a credit to the AI that it has put up with my ham-handed modifications.

[nikdav]

I already extend the support for all scenarios to 33 or 90 (campaigns) turns after the official end.
You can also easily change last official turn in the simple editor and save the scenario with different name!