2. my background is white mylar that is backlit with two alien bees strobes with the standard reflectors aimed at the back wall. subject is about 4-5 feet in front of my background. The light spilling from the back is a compromise between available space and flash settings. It reflects off the back wall, lights the mylar, and some bleeds back on the mannequin 4 feet away. I've played with angles, built custom stands to hold specific cross over patterns. This set up generates the least editing of all my other iterations. I overthink this stuff big-time. I'll spare u the details.
Try the sheets of white foam core between the BG strobes and the subject. Something like this: