dc32f0cfe84def651e0e This doesn't exactly do what you were hoping for but I believe that the GOS team are currently working on a feature that adds a pin code to fingerprint as a 2nd factor for unlocking the screen. This makes fingerprint unlock more secure and would hopefully mean you only need to type in your full password less frequently. So your password, for when the profile is in BFU state, is less likely to be 'snooped'.
Also, if anyone is experiencing a bug where switching between already unlocked and running profiles causes you to need to enter pin/password instead of allowing you to use fingerprint, I am pretty sure that as long as you only have 2 or fewer fingerprints registered in each profile, this should fix the bug (as things are right now anyway, the next update from Google may change things as this is an upstream bug)