I found this amazing blog post Fat Sex: What Everyone Wants to Know But Is Afraid to Ask where Ms. Vagina Science breaks down how a fat girl can have sex with a skinny guy (sex positions and all):
"Pillows are a fat girl’s best friend during sex. Next, find a firm, yet springy surface to do it on. Pillow top mattresses and memory foam tend to not be as easy to have sex on since you sink down into those surfaces instead of bouncing back. Next, get some decent water-based lubricant, just in case. I’ve heard a lot about fat women having big vaginas, which honestly doesn’t make any sense at all. The vagina is inside of the body. That would be like saying that fat women have bigger kidneys just because they’re fat. It’s nonsense.
What’s far more likely is that you may just encounter the opposite – a fat woman’s vagina can be hard enter, especially if it’s not properly lubricated. Fat women can have more padding around the vagina (on their mons pubis and labia) than a thin woman, creating a potentially tricky situation. If your partner tries to enter your vagina when it’s not sufficiently lubricated or doesn’t take the time to part the labia, there can be resistance. If you’re lubricated well and take care to spread apart the fat surrounding the vagina, you should be good to go."
I love her candor and her pics for each sex position. You may be limited to missionary, woman on top, and modified doggie but those are my favorites.
Looking forward to more from Ms. Vagina Science.