Taming "spiky" AC voltage source, need to reduce the max amplitude
I think your option 6 would be the easiest to implement.  Analog devices (via Linear Tech) makes the LT8631 high voltage step down converter shown below.  It can take up to 100V input, so it can be driven from the output of the diode bridge.  However, the BOM cost would probably be closer to $10.  It might be worth it for the ease of design.