JT
You asked about conditions at the stall. The manoeuvre I am thinking of is the wind up turn (WUT). It is a very common and bog standard flight test technique used in all development and certification programmes to establish the Manoeuvre Boundary of any aircraft (how much g can it pull at what speed)
The technique is to start at the test height and slowly increase alpha at the required speed until the stall. Once full power is not enough to maintain speed (ie at the thrust boundary) you overbank and lose height to maintain the speed steady.
The aim is to have quasi steady state alpha and speed (albeit with changing height) at the stall (a bit like the must be less than 2kts per sec speed reduction used for 1g certification stalls) Once the height loss is significant you start the manoeuvre above the test height and (if you are lucky) have it on condition as you pass the height.
As I say this is bread and butter of flight test but always produces points that sit on a curve that is a tad less than V squared. And that despite the beneficial effect of high power which has to have a small component assisting lift (indeed not so small at high alpha)
It is this gradual reduction in Cl max as speed increases that I have always been told is down to compressibility effects.
JF