You can already do this. Use the second screen option - if you only have one monitor, it gives a floating panel. Also, switch on AutoSync and leave it on. Then whenever you have mutiple files selected your adjustments apply to all the files and you don't need to spend time going through SyncSettings.
Oh, I see. I've been ignorant.
I can set the second screen to "grid view" and the primary to "develop".
If I could reverse that, so that the grid was on screen 1 and the image being edited was shown on 2, that'd be perfect.
Why that way around?
Because on screen 2 there is more screen real estate for the image that I'm editing - much less screen real estate is lost on the left, right or bottom to strips, be they the disappearing kind or not.