I... create custom poses for The Sims 3 using Blender, import them in the game and then take screenshots in there to use as reference
it's probably not the fastest method to create a pose and it takes a while getting used to Blender, but at least when I rotate one arm in Blender it doesn't rotate the whole friggin' body as it does on CSP. Also, although you can't technically change the size of the mannequin in Blender itself, once in The Sims you can create characters in a variety of body shapes, customize their faces, clothing and so on and so forth.
Here's a tutorial, in case you want to check it out: https://sims3cliptool.wordpress.com/tutorials/completeposetutorial/
A very similar method can be used for The Sims 4 as well: https://www.youtube.com/watch?v=eRYrJ1w6RZM
Not sure if any of that would be feasible for you, but I figured I'd throw it in there as an option :'D and even if you don't own any Sims game, I'm pretty sure it'd be possible to use a similar method to edit just about any 3D mannequin that comes with a rigged skeleton.