I think (from my questionable experience) what would make going for these ambitious poses is to start the drawing by marking out the light sources and shapes first, without the aesthetics. You can checkout out the early stages of WLOP's timelaps paintings. They are classically/principally formed and the beauty of color and style reveal in passes.
Right now there's a consistent amount of light color where I would expect a complete absense of natural light Below the elbow. The elbow shape in contrast to the foreshortened arm is the most important thing in this scene to render (even over-emphasis) simply because it is a controrted position.
You may be able to increase the contrast on the 3d model to see how the forms are actually presented. I'm a big believer it should look messy at first and as you add things like color and clothing the painting.
Not sure if that helps.