Before Lands' End started selling bathing suits, I hated shopping for them, primarily because I have a long torso and long/tall one-piece suits were impossible to find years ago. Lands' End has a virtual model on the web site where you can see how different suits will look on your body: www.landsend.com

It's not perfect, but you can get a good idea. And they make suits for mature bodies, not stick-figure models.