Oh, yeah. Didn't even think about that guy. Sam could potentially work in the role. And you wouldn't need to worry about a slightly younger Chewbacca because Peter Mayhew is always draped in Wookiee makeup, so a Sam-Peter team might be feasible.
I'm trying to recall when Han was booted out of the Imperial Academy for disobeying orders and freeing Chewbacca from slavery....the graphic novel makes Him look like he'd reached his early twenties by that point and the fact he was in the Academy would also point to an age between the end of his teens and his early twenties, which means the film could be set 7-10 years before A New Hope