I'm thinking of just lifting them all up, dividing and cleaning and moving them to an existing bed which has good drainage. I'd move all those plants up to the old iris bed, where most of them will do fine until I finish the great rearrange of the gardens. (As an aside, I'm thinning my daylily collection, and otherwise changing the garden up.) New bed is unlikely to become shady in the next decade.
My other concern, is since this new iris bed will be "front and center", it will be boring unless I find some good companions that like the same summer conditions.
So - Make the move now while I have the time or wait until it starts to cool down and hope I have the time. Watering is not an issue.