Hi Marc,
afaik BMD is using TiCo compression/codec for the Camera / Studio Fiber Converters. I think there have been a lot of posts about this here. Try to search for „TiCo“.
That being said, I think there is no way to get a „simple“ Sync signal transferred. TiCo is just compressing SDI (the video portion of it) signals.
https://www.tico-alliance.org/technologyYou could try to PM forum member Daniel Wittenaar from xtreemtec.nl as he has a lot of experience and some custom build goodies for the BMD Fiber range (even a working solution for RS422, I believe).
Maybe that helps a little.
Knut