Well what if this idea started out in ROTJ where we find a different ending where the rebels fail and are wiped out by the empire. The film would then end with Luke (by way of instruction of the spirits of Obi-Wan and Yoda) managing to use the force to go back in time to stop the empire's formation. It could work as kind of a"X-Men Days of Future Past" kind of story. We follow him tagging along the journey of Anakin and Obi-Wan (possibly going by an alias if it would be preferred to keep Anakin and Obi-Wan unaware of who he is). By the end we would find Anakin in a situation akin to the end of ROTJ where the Palpatine has revealed himself and is about to kill Luke. Anakin ultimately kills Palpatine, thus not turning to the dark side and preventing the empire's formation. Luke ends up in a peaceful future where the Jedi knights are still protector's of the Republic, Leia is a diplomat, Han is a well respected general, and he himself is undergoing proper Jedi training. Ben and his father are both still alive and good friends. The future is left open to other stories and everything that has come before ends happy.