Assistant DM mode.

Someone who can drop in tokens as you describe events, work the Turn Tracker, even play music, but not see the Dynamic Lighting or DM layer.

I was going to say you can promote someone to co-gm but then I read what you said about them not being able to affect the dynamic lighting or see the DM layer. I agree something like this could be helpful, that or modify the existing promote to co-gm to have a selection box so you can specify what a user can or can't affect

That could be very useful.

+1 to having a way to limit the power of a co gm. Though, it would be tricky to implement in a useful way, with so many different things you might want to allow, or disallow depending on the situation. Where do you draw the lines? Permission on a per map, and per layer basis? You would have to have some options on the page settings dialog boxes, the promote to gm dialog box, the campaign journal, and possibly somewhere else, depending on what type of limitations you wanted to set...... I think it would be doable, but it could be hard to keep track of.

I think that in the beginning it could be as simple as giving some global options when you promote the co-gm. Like a token where you can allow the owner to see or edit a portion of the token, you could do that with the co-gm. That would be just the first iteration. As time went on the new system could be expanded to fit the needs of the GM's.