It appears from this study at least, that RES female x GSF male is the preferred cross from a growth standpoint. The start of this thread was a study of GSF female x RES male.
Contains info on back crossing also.
But according to this study the GSF male x RES female did not cross successfully in a pond environment setting, where the RES male x GSF female did.
So it looks like I'm back to stocking the proposed pond with RES then adding a few GSF females to get the GRES cross.
Hybridization of fishes in North America
