You can call Marriott Rewards and ask about a challenge. Recent posts here, including one of my own, seem to show that Marriott is a little more willing to hand out challenges rather than status matches.

Also, since you already have almost 50 nights, by the time you make a Gold challenge, you will almost be a Gold anyway. So you would be much better off asking about a Platinum challenge. And if you haven't already applied for and received the Premier Signature Marriott Visa, then you might want to look into that as well. It will come with bonus points, a free-night and a golf cert, plus give you 15 nights toward elite status. (Instand Gold for you if you do nothing else.) ^