Several reasons this is Not Sitzman. For starters, just look at your own model. Sitzman is tall enough standing on that 2nd step to already see over the picket fence. Why would she then be BENDING OVER at the waist?
She is not only able to look over the fence, but also beyond the pergola shelter into more of the parking area. The further she moves down the steps the more she could see in that area.
Also, why would she have her left arm extended straight out/perpendicular to her body?
Balance?
Contorting Sitzman's body into this "Twister" position is not natural.
There is nothing unnatural about that "Twister" slur.
And what happened to her scarf that runs down her back?
Over her right shoulder.
Really? You claim, "The further she moves DOWN the steps, the MORE she could see in that area". Not true. The further DOWN the steps anyone goes, the LOWER they are in relation to the picket fence = the LESS they can see. High ground permits a better view vs low ground.
What woman inna standing position has her entire arm extending outward at waist level? There are 3 Zapruder still frames showing Sitzman standing. In all of these still frames her arms are tight to her body. Including her arm with the purse draped over it. No arm is sticking out from her body.
If you're gonna turn that scarf, (for whatever reason), with the rear duck tail now over her (R) shoulder, then the KNOT that was under her chin has to now be over her (L) shoulder. That KNOT is not visible on the guy/kid looking over the picket fence.