Hi King
To the backcross, i can say, if you want the strain like one of the parents is, a backcross is a good thing to stabilize.
With my other project i got the same plan. I will cross a photo female with a auto male, work them out to full auto in f3, breed them to f5 after then i do a backcross with the photo mother and breed them again to full auto.
After that i will have a autoflower strain who is stabil and is near to the mother plant in taste grow and high. I think at generation f5 the strain will be stabil.
cu tobe