well... when I was 20, I rode from Ohio to Florida, averaging 85 miles per day, with one 117 mile day in the mix (my first century). In the 30 days before I left, I probably rode a total of maybe 40 miles. But I was in pretty decent shape.
Point being, yes it can be done, especially at that age. Just don't be in a rush, and personally, I'd drink more than I thought I needed to. Maybe a bottle every 10-15 miles or so.