Hi Harris! The only way I can think of to establish symmetry in a situation like this is to rotate the model itself until it’s aligned as closely as possible to the axis you want to symmetrize. You’d have to do what you describe as far as adjusting the model as you go. You’ll probably have to hide some parts of the mesh or create separate retopo objects because Retopoflow will complain (and want to fix) anything it sees crossing the line of symmetry.
