Not really an answer but it might be worth looking at. It's a plug-ib for NPP called Window Manager, it allows a slightly different view of open documents via a dockable window. It can be found at the bottom of the NPP plugins page

Not really an answer because I'm not aware of any specific tab management plug-ins, but it might be worth looking at. It's a plug-ib for NPP called Window Manager, it allows a slightly different view of open documents via a dockable window.

I have it installed in NPP and it's useful when there are multiple tabs open. It can be found at the bottom of the NPP plugins page