I will definitely be using tab and bouncing from now on. It is nice to know that tab will stay in the mob only. Also, bouncing while offtanking also makes sense to keep from stealing aggro, though as I tend to be MT that is less of an issue for me. All of this advice is working quite well: I am much better at holding big group aggro now, though some do still get away from me off and on. And BSV is still hell (multiple big mobs are just awful!)
Thank you all for the advice!
Quijana