I just ran across your post and I'm curious if you're still looking for ways to effectively simulate bariatric patients?
There is a company that makes suits to place on your manikins to create the look you're going for. On top of that, you can add weight to create real training with heavy patients. The website is www.simusuit.com. I currently am the sales manager for Sim U Suit, so if you have any questions, please don't hesitate to ask!