Obese people are very hard to model for many reasons including as you mentioned lack of off-the-shelf morphs, but you've done pretty well here. The legs and hip area in particular are well-done.
If you're going to work more on this model, I would suggest that unless she is extremely short/practically a dwarf the head needs to be a quite a bit smaller; also the hands and feet seem to thin/made thicker/fatter.
I have never conformed Poser clothes or
