When the tongue weight gets up around 1,000 lbs and upwards, the threads made by the Reese forming screws can be become enlarged/ovalized and the screws can become loose. This happened to ours and I am planning to take care of this before the next season.
If you only tighten the Reese forming screws directly into the frame, I would periodically check the tightness. There is a long, long thread somewhere on the forum about this. There are some ways to overcome this if it does happens, such as through-bolting along with a spacer inside the A-frame. The radius of the cam arm bracket is different than the outside corner of the square tubing on an A-frame which can worsen things too. For higher tongue weights and a Reese DC WDH, the long, long thread is at the very least, an interesting read. Couldn't find it in a quick search though.