When DRGs enter Dragon Blood mode they get an effect on them that persists for the duration of the buff. Why can't SMNs get a silhouette of Bahamut around their body whilst in Trance or something like that? Maybe even just claws or wings? Just something to indicate a partial transformation. When Iceheart summons Shiva she transforms into Shiva. What we're doing with Bahamut is the same thing so there should really be some kind of transformation that lasts the duration of the trance.
This would go a LONG way to making Dreadwyrm Trance feel more like a summon and less like an arbitrary cooldown.