Thought I'd share this. Made up a split view, as a larger drawing sheet was swamping the amount of information I needed to put on it. Create two sections, manually brought the borders in , roughly aligned. And put an overall dim on there. The overall dim, I had to zoom right in and just click somewhere near the ends. I thought about flattening the view but it doesn't flatten that little bit, it flattens all of it.

Then overwrite the dimension with what size it is.

I'll try and stream line this a bit