descending steep driveway

On a re-read of your post I see that your concern is a little different than what I first thought. It sounds like your primary concern is hanging the trailer on the edge of the road as your tow vehical starts going down the 16% grade whether your hitch will take it. Your are talking about less than a 10 degree angle and I have launched a lot of boats on ramps steeper than that with no hitch issues, even with the torsion bars still attached. I am fairly sure that the hitch is fine. The only issue that I have encountered is dragging the trailer about midway between the hitch and the front trailer axle. At the point where the trailer is dragging the hitch is well past the breakover point and the torsion bars have already cleared. Let's say that you have 200 inches from the center of your axles to the hitch and that the angle is split between the vehicle and the trailer(think of a hump between the trailer and the tow vehicle with an 8 percent slant on both sides so that the difference is 16 percent). So if you go forward about 100 inches to the midway point(or about 8 feet) and go up 8 percent (which works out nicely to 8 inches) and you have plenty of clearance your trailer should not drag even if it is a sharp break. If anything was done to break the angle you will be that much better off. I probably would not want to try it in my motorhome but most travel trailers I have seen have plenty of clearance.