Honestly I think it is the best solution, only thing you could do (if you are using PiP-Swaps), is to bind the '/jamba setmeasmaster all' to the button you switch your windows with, so maybe you could 'save' a keypress...
..other than that, I would do exactly the same.

If Jafula finds some time, maybe a new command, where you could specify another Toon for beeing the 'Quest-Master' would be handy (like /jamba setquestmaster <target> <tag>;), but honestly I don't know how much people would use this, as this is mostly only a problem, for people who boost toons, and often for instance boosting you don't need much quests to be handled...