Options for displaying a wide UIList within the UI?

What are our options for displaying a wide UIList within the UI somewhere? Right now I’m using the VIEW_3D/UI space-region combination per the below screenshot but it’s not very ideal.

Ideally I’d like a panel I could stretch the width of the viewport – almost like replacing the “Timeline” editor with this custom Panel in the “Layout” Workspace. Is filling an entire editor’s space possible? What are some other options for something like this?