Although I would love to explore the ruins of Valyria in depth, it's been pointed out to me that we can't really devote as much time to that as would be necessary to do the job correctly. That said, we've still got up to two weeks we can spend on this expedition before things start to get out of hand.
With that in mind, I propose that we establish a fortified base of operations in Valyria before we depart. It would need to be in one of the more habitable areas, unless we can take steps to render a chosen location more hospitable to human life (via specialized Heart Tree, perhaps).
Using a set of Titan's Tools, a large walled compound with a easily defended keep or tower could be constructed in a day of work. Kira and her Violin of Building can take care of the followup finish work. Some basic warding (Forbiddance and Hallow) would help secure the compound from hostile intruders. It would take quite a few trips using Teleport to staff the place, but we've got plenty of Companions who could help Viserys with that.
We could then base a party of B-team adventurers, a couple squads of Minotaurs, a detachment of elite Legion soldiers, a group of Scholarium mages who need some field experience, assorted Plant creations (Verdant Wolves, Giant Fungal Darkenbeasts, etc.), and a few of Erinyes to not only stake our claim to the continent, but to also explore the region more thoroughly. The Archons of Mantarys probably wouldn't mind stationing some of their people there either. It should be a great way to get experience for everyone stationed there.