Conformal Coating masking

Hi there!

We need conformal coating on our next PCB, but we need to mask out buttons, connectors and a diagonally placed battery holder.

I read the remarks about the 17x17mm spray area and keepout options. But I'm wondering is we can still mask out an 17mm wide area diagonally? Or is the entire board divided into 17x17mm squares? Please see picture attached of an example. (Don't pay attention to the components on the board illustrated)

Thank you!