There are a lot of them!
How big would you want your BBW? There are a lot of bigger girls in the industry but if you like really extremely big its gonna be more difficult.
As for older women, there are a lot. You may be discouraged because not many women are listed as being 40 on p4p websites, but sometimes the ages listed on the website are 10 years younger than the real ages. Are you looking for FS or not per se? If you want everything done in English and FS, look at Asian Mystique. They dont list ages on their website but a lot of the women are over 35, according to the reviews here on TAG. Recently, and older women (50+?) called Sakura joined AM (not sure if she is still there). According to recent reviews, Asami and Rio are also over 40.
Nozomi from Nasty Dolls may also be an option, she is a veteran at the job.
If you are ok with gaijin friendly but not english speaking and no guaranteed FS, there are cheaper options like sexy cat, new york new york, jan jan, happy hinomaru and that delivery health in Gotanda with older women (i forgot the name).