I think it's true that remote-control of a pet tank is too complex for party use. It would be impossible to position correctly or respond quickly enough to mechanics.
For this reason, I am a fan of the approach where the BST is channeling an animal spirit and tanking directly, possibly while riding a beast or having one that will provide buffs. For example, once a beast gauge fills, a pet could be called to provide a short 20% buff, like WAR's Inner Beast. The channeling of a spirit guide animal would lend this class well to a very primal feel, like someone from a tribe that lives off the land. I picture this with dual-wield tomahawks. A whip is obviously another good choice, but personal preference is for dual axes. Dancer, or dare I say Blue Mage could have whip.
Definitely take the transformation or channeling approach to this job, more than remote-control tanking like a Titan Egi.