If Minato studied some Uzumaki seals, culminating in the one he put on Naruto, why not use Mito’s seal? His lover is a jinchūriki, which gives him all the more reason to study up on the bijū sealing methods Konoha possesses. Mito didn’t die sealing up Kyūbi, and she’s an adult too. So surely that seal wouldn’t have killed Minato and Kushina? Though to make things estranged between father and son, Kushina can (and should) die.
In that case, the Sandaime is obviously not burdened by governance, and helps take care of Naruto. Naruto is always in the shadow of his father, and wants to prove himself by being different. Minato sees all of Kushina’s personality traits in Naruto, and finds it hard to deal with the loss. The Uchiha coup is dealt with differently since Minato is in charge.
Will this prove to be different and fresh, compared to other stories where Minato lives/family estrangement? I don’t know, but the premise is somewhat different. If I do pick this up, hopefully I can do a good job with it.