How to extend measure playback duration MS4.2.1

If I add a pair of repeat barlines, I can set Measure Properties > Play Count.
Is there a way of doing that without a pair of repeat barlines? eg for an aleatoric bar where I want the playback to extend over a fixed time such as 30 seconds.
Maybe a property of the Symbol Right (end) Repeat sign if placed inside the bar, not as a barline at the end?
If I should post this to Github, just let me know.