FWIW--we did a shot in our studio several years ago, where we needed to have the subject blur/movement like you'd get with a rear curatin sync. On our 4x5, we lit the set with both hotlights (gelled) and strobes. We wound up burning in the motion with the hotlights and then firing the strobe manually at the end of the exposure.....the subject in this case was a hand being jerked back from a steaming pot--via dry ice in water--we timed the motion of the hand & arm of our patient model, with a timer from the lab set on metronome....it took a couple of trys to get it right, but worked & was an interesting diversion from the usual types of shots we do....I realize this is sorta not the right answer, but this is the way we dealt with this problem--we didn't have much of a choice otherwise. BTW-- in our studio we shoot with multiple pops 99% of the time and most times we don't even use the shutters.....we even work on location like this when shooting interiors--using strobesto blow out the ambient or cover the lens between pops......

it seems like I remember seeing a device for studio strobes that would enable them to work like this....it's been awhile, so maybe my memory is just daydreaming here.....

KT