I'm sure a 50k would not be a primary focus. It would be like focusing on a 15k race when there are all kinds of big 10k or half marathon races to choose from. Go for the big one. That said, you definitely have a lot of room for PRs at that distance.
I guess the Coke thing didn't catch me off guard because I remember Coach Conway talking about having a friend hand him a defizzed Coke at around the 20-22 mile mark of marathons. He said it was a great pick up for the late race when you feel like the wall could be just around the corner.