There was an article recently, don't have a link handy, that described what you're proposing to a dot, CentexHusker. It was about RB coach descending into his laboratory with his four backs, which spews smoke and emits evil laughs for a few days, and emerging with a spliced-together FrankenBack. It also described the amount of frowning the NCAA would do at this.
And how they would ban future player-morphing in the game.
But I don't think we'll have to go that route. Just run 50 times a game