None of these solutions are easy to implement. And they have their own share of pros and cons. But before you pick either solution; you have to ask; is it even really necessary to bother?.
The second is the way to go, but its not easy as you say and would require engine restructuring. Some day I'd like to add support because just being able to have one camera set up on each screen. One watching Normandie, the other watching the pacific would be super convenient.