FTDK, Section 2 of the Aerobat POH actually does use the words "Inverted flight prohibited" and does not approve "Whip Stalls", aka Stall Turns or Hammerheads.
Having said that, we used to do a pseudo stall turn by taking the aircraft to the vertical and as the speed fell to 40 KIAS, applying full rudder in the desired direction and keeping the wings in the correct plane with judicious use of aileron. Lots of fun and the aircraft never actually "whip stalled".