I would not attempt my child on my outback although it could be done.
With that in mind... 8 years old seems like a great age to start soloing in the bay with dad in tow... and it seems that a cobra tandem (similar hull to FND) would be a great solid platform for her to learn on. Then you can get your choice of the outback or revo for you. And you still have the ability to go out together under paddle power if you choose!
my 0.02