Great points, thank you. I am reassessing my thoughts on this based on the "cooling thoughts of expression". I do think the Reagan example is a big deal though.
Let's say you spent your life in defense of equal/civil rights and then after you are dead you ask your daughter to continue your struggle, she proudly agrees. Then the KKK starts using your likeness to recruit new members in a marketing campaign that is wildly successful. Currently, does your daughter have any legal recourse? If she clearly owned your image, she could put a stop to it. This seems pretty clear cut. How to determine if it's just a similar image/style or actually meant to be you would be difficult to determine in some instances but then that's why the jury exists.
Not just being contrarian, I don't think there's any problem with the KKK using an image of someone dead. They could use George Washington or my grandpa. I wouldn't like it, but I don't like the KKK to begin with. You can always dream up extreme cases, but they shouldn't be the guiding force. Some scenarios like this might be distasteful, but it's not reason to institute property rights over what the living deem a dead person's persona to be. I think the medicine is far worse than the disease here. We don't stop vaccinating because the adverse risk is non-zero. Most people don't want to end up in front of a jury, whatever their chances, so that pressure would prohibit a lot of expression, and IMHO pervert the historical narrative.