Back of Illustrated characters (from behind)

I'm afraid the best solution is to export and modify the existing characters to your needs. Many of the illustrated characters are simple enough that minor edits can get you fairly good results. If you need some extra refinement, you could always make some basic edits, and then run the intermediate image through a generative image ai model.  For this example, I took a front picture of Norene, painted out (Krita, free) much of the front detail, blocked out some basic shapes for the hair and shoes. erased anything that should be hidden, and ran it through getimg.ai (free). This blends everything together and fills in some missing detail. Do any needed cleanup in an image editor. If you have access to a vectorization tool, that will help smooth all of the edges and make scaling look better (import into SL as an SVG). Takes a bit of work, but eventually you will have a nice library of characters. This one took about 30 minutes and was my first try at it