A few interesting thoughts in this thread.
Perhaps I can make some observations.
(a) book Vmca is extrapolated to sea level during the certification program so, unless your POH specifies the value for other than SL, presume that to be the case
(b) provided you are either non turbo/supercharged or above FT height, the real world Vmca will decrease with increasing height
(c) book Vmca is for pretty much worse case circumstances, including aft CG
(d) the above indicates that real world Vmca usually is less than the book figure which is why folk can operate as IAS less than book Vmca value hence the observation
The Vmca is ca 70KCAS according to the flight manual.
THe buffeting occurs at lower speed around 60.
(e) one of the pertinent problems with Vmca demonstrations is that we do those at some height .. and with increasing height we usually have the problem of Vmca being near or less than stall.
(f) if you stall with significant yawing inputs (rudder or asymmetric thrust) you invite a spin.
(g) you will search a long time before you find a POH which suggests that you should be playing with asymmetric stalls - potentially very dangerous stuff
(h) the certification stall techniques have varied over the years. Tee Emm refers to the Beech - with some Baron models, even holding the approach to the stall into a fully developed stall invites an uncommanded inverted spin - and that with throttles at idle - food for thought ?
The Vmc demonstration is accomplished with the critical engine WINDMILLING. Which means full idle, but not set for zero thrust. Doing this maneuver with zero thrust set could get you into big trouble.
I'm a bit confused here - why would zero thrust be a problem cf flight idle ? - presuming that you are not talking about some oddball aircraft systems problem.
once the ac is unstalled (above Vmca) feed in power/rudder, and if the speed is sensible use some aileron.
you can do anything with a plane as long as you have enough time to sort it out if it goes wrong
.. and, if you are already in a spin ? which may be not readily recoverable .. methinks your (over) confidence might exceed your knowledge and experience.