I think I would work with the PoCo engineering department and try for the center tapped delta. You do have to be careful with the load balancing if they only give you 2 transformers. If they do this in "delta vee" you can drag the wild leg around with unbalanced L/L 1p loads.
If this goes in as 208 wye the customer will need to replace a lot of equipment, either now or when it burns up. There is not a whole lot of consumer grade stuff that is tappable to 208
