The question is “How many people would shop in a chic, stylish plus size women’s boutique?” Not “will the benches be able to seat Popa”? Frankly, I don’t think you need to concern yourself with spending time in a women’s clothing store of any type.
To expand on an above comment, Dress Barn stores have separate sides for regular and plus sizes, but many of the same styles. I think that is a great idea.