Instead of just one row of open view tabs, provide multiple rows of view tabs so that more open view tabs can be visible.
Each open project's view tabs could be in a different row.
Allow users to select the maximum number of view tab rows they want to display, with a scroll bar / arrows to scroll down to more open views.
Use the middle mouse button to pan open view tabs left and right, and to pan up and down to multiple view rows.
Provide sort options for open view tabs - Sort by project, by view name, by sheet number, by view type, by last viewed, etc.