Looking at the ground, steep turn slow in 20 kt winds. Seems to me configuration wouldn't matter much. When you turn from downwind to a crosswind and on to upwind, the drift over the ground causes people to instinctively tighten the turn. Pull too hard and you high speed stall.
Check c of g and flap rigging (symmetrical) if you want to try blame something else. As far as no stall warning, which wing is the stall warning device on and which wing had higher angle of attack?