Late to the party on this thread, but I found it looking for this topic. So I'll add my current solution.
I registered my print using a small section of an atypical area of my thumb. With a little practice, I swipe that now by habit but it would not be obvious to a casual observer that I'm doing anything unusual.
Since it's a small area and a part where the print is less distinct, the trick to make it work is to register that same area twice as 2 different fingerprints. Registering it once, the success rate for unlocking was less than 50%, but doing the same area twice and with a little practice it's just as good as a normal print. If anybody physically forced me to swipe my thumb, it's a near-zero likelihood that they would get it, and then the pin is required after failure; even if they saw my unique swipe and tried to make me do that, the exact spot and angle required would make it very hard for them to get right (and easy for me to mess it up).
So for my risk profile (i.e. I'm pretty boring and not a surveillance target for any particular reason) I have a solution that's reasonably cop-resistant and reasonably over-the-shoulder resistant. Obviously part of the solution includes that, aside from posting here anonymously, I don't talk about it.