I am still experimenting with a good max width. I think in this one I set it to 450px. What would you set it to if you had a choice? I don't really want to add a setting of this nature to clutter the settings page. This is something I might have made a hidden about:config setting in the past, but that is not an option right now.
The best right click menu I can think of adding this too is when you right click on the tab bar. I could show some kind of menu there. Would this work for what you are looking for?
It is best if you get in contact with me on my forum or by e-mail.