If this level turn is balanced it would indicate that some power & trim had been applied to maintain this balance. If the turn is balanced the aircraft must be travelling at a constant airspeed. Therefore although the outer wing is describing a greater diameter than the inner wing, the two wings are balanced by nose up trim & power+. How can the a/c stall in such a balanced condition? & why would the outer (faster) wing stall first in the unlikely event that the laws of physics have been broken?
I have set my Emeraude up in a balanced level turn & taken the hand off the stick to take photographs, it takes a bit of care to get it balanced well enough & ensure it is going to stay there, but not a problem. I must try it one day to see how long it will stay balanced before it falls over!