Too many expanding panels, not enough room

The scenario: An enterprise software platform uses a collapsible left panel for its navigation and a collapsible right panel to show customer info. The customer info panel would be used side-by-side with the information in the main section.

When fully collapsed, there is a lot of room for the main gridview.

When fully expanded, the panels push the gridview's content in. We thought this wouldn't be much of a problem.

But, that's not how gridviews look in real life, right? They're looking more like this:

The question: The left nav can collapse when the mouse leaves it (and re-expand when the mouse enters), but what should happen when the user opens the customer panel, and there isn't really enough room to compress the gridview?

We thought about opening the panel over the gridview (vs. pushing it) but it seems like the right-most gridview content will get covered up, and the user wouldn't be able to see it without hiding the panel, which isn't ideal.