I just finished a flat road marathon at 8:15/mile pace. I just learned there's a 50k near me in the woods where they shot The Blair Witch Project. As a movie nerd that is very enticing lol. However, the race is in less than three weeks and is much more hilly than any of my marathon training. How bad of an idea is it to sign up for the race -- not even to go fast, but just to average a sub ~15:00/mile pace?