Does a solo pilot performing aerobatics constitute an "occupant" for the purposes of requiring a parachute per 91.307(c)?
If you're solo you don't need a parachute (emphasis mine):
Unless each occupant of the aircraft is wearing an approved parachute, no pilot of a civil aircraft carrying any person (other than a crewmember) may execute any intentional maneuver that exceeds [...]
Incidentally, 91.307 says nothing about aerobatics; that's in 91.303.
And this question is closely related.