It's been so long since I've stopped doing all my curation automatically. At this point, manually curating is just a part of my day. I love using lists on PeakD to organize who I vote for. If one list has less activity than normal, I just jump to another one so that I never have to worry about not using my daily votes. I enjoy it and wouldn't have it any other way now. It's really not that hard to do once you get in the habit of it.
If there ended up being a way to receive an additional reward just for doing what I'm already going to continue doing, then I'm all for it. It really does seem like a difficult task to figure out a way to verify which votes are manual and which are auto. Perhaps one of the popular front-ends such as PeakD or Ecency could implement a feature that somehow keeps track of when a manual vote goes out. I know Ecency already rewards its users with Ecency points just for using the app, so the data is already there. You of course don't get the points for auto votes.
You've got some good ideas too and I'm sure that just putting this out there will encourage some minds to consider possible changes that could help further encourage manual curation.