Series diode instead of a flyback one
No.  If the inductor were perfect, and the switching of the FET instantaneous, then the inductor would generate an infinite voltage when you turned off the switch.  Even in our imperfect world, putting the diode in series with the FET source will just burn out both devices while protecting neither.

Inductors do not want to change current instantaneously.  You must give that current someplace to go when you turn off the FET.  There are various ways to arrange catch diodes, but you have to answer the question "where will the current go if it WILL go someplace?"