You don't need (or want) rim light on the subject using a blown-out background. The whole point of the rim light (or hair light for portraits) is to create separation. A white background naturally creates separation. Indeed, you really should be lighting your subjects and background separately, but it sounds like the dimensions of your studio don't allow for that exactly.
I know you were attempting a certain affect, but maybe blowing out the background isn't right for your concept. First, the white background seems way too sterile for the b-boy subject. I know, I know: juxtaposition...but it doesnt really do too much for the dancer, either IMO. Maybe you could illuminate the subject and allow the white seamless go to gray.
PS: Where are you getting this great Profoto and Elinchrome gear?
