Hi Boourns,
This post make take a few edits to get the ASCII right, please bear with me 
So I was reading through the discussion here, and it occured to me that the basis of the 'locked camera' problem boils down to where the champion is centered. So what about an option that lets you adjust where your character 'rests' on the locked screen?
I'll demonstrate.
Current locked camera screen, featuring Teemo:
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(more or less)
Now, imagine you're a locked camera player. You sign into a game. Oh Noes! You're purple. Never fear. You walk to lane, and at your tower, press and hold a button marked "adjust locked camera." You scroll your mouse to the bottom left, and your screen (slowly) pans from the above screen to this:
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|~~~~~~t~~|
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Now your field of view is roughly equal to your southwest and northeast, thanks to camera angle and depth of field. You release the "adjust locked camera" button. Your screen now remains this way for the rest of the game, or until:
Oh Noes! A teamfight is breaking out, and the new off-center center that was so useful in lane is now a real problem. No worries! You just tap another button, labeled "restore locked camera centering" or some such, and boom, your screen re-centers itself on Teemo. Problem solved, and you can always re-adjust as necessary.
Seems like it would be a good middle ground for people who don't like the default locked camera view all the time, but also don't want to have to constantly adjust their view while they try to play. 
Edit: an even simpler way to deal with this would be to make the second screen an alternative locked camera view. As in, two options for locked camera players: Locked Camera (Normal), and Locked Camera (Purple). Personally I like the custom-movable version better though.