It has been 3 weeks since my first, rather disappointing attempt at exploring this but in that time I have given the whole thing some thought and yesterday I got to have a second go.
In post #1778500 Longfinal spoke about flying the manoeuvre at a much slower speed than the climb trim speed I accepted previously. That made a lot of sense to me as a slower speed will result in a smaller radius turn, a shorter path round the turn therefore less height loss.
So I planned to climb at my normal 60kts, cut to idle and, again, hands off the stick allow the pitch trim to maintain flight speed but, as we arced over into the descent I'd pull the trim fully aft. That would give a trimmed speed of 50kts or so, about 1.3 Vs0.
This is how it went:
1 was in my climb out from take off. Continuing the 24 runway heading to 1000ft I cut power to idle. 20 seconds later we were pretty much round and straight on the reciprocal 06 approach. Altimeter reading 910ft. Height loss, 90 ft. Bank angle was a little less than 45°, probably about 40°.
2 was initiated at 2200ft, same procedure as before re-trimming as we arced over. This time completion height was again 910 ft. Height loss, 110ft! Bank angle in this one was steeper, probably closer to 55°.
3 began at 2000ft, bank angle about the same as in No2 and completion height 900ft. Height loss 100ft.
In all attempts time to reversal was within a second or two of 20 seconds.
This was much more what I had thought I and my little aeroplane might manage though I hope that in a real EFATO I would still be cautious about a turnback at very low heights.