^^^ This.
Single axle trailers tend to "seesaw" with the axle as the fulcrum, which will constantly load and unload your tongue weight. This can increase dramatically if your tongue weight is not distributed properly. MOST boat mfg's design the trailer that when the boat is loaded, the tongue weight proportions are quite close to correct...however, if your hitch is either too high or too low, it will throw off your weight distribution. Here's a good rule of thumb in selecting the proper drop for your hitch:
With your trailer unhooked, use the jack and raise/lower the trailer until the frame rails are level. Measure from the ground to the top of the trailer tongue at the ball socket.
Now measure the height of the ball on your hitch. Ideally, you'll want this measurement to be about 2" higher than your trailer tongue to account for squat once you load the ball.
As far as the sway bar comments....don't bother. Your 4th gen Ram has a 5-link rear suspension: 2 lower control arms, 2 upper control arms, and a track bar. It already comes equipped with a sway bar. At a 3500 pound trailer, I wouldn't bother with a weight distributing hitch (trailer sway bars,) it's just not enough weight to justify it. Installing some air springs in the rear will definitely help also, but again, at 3,500 pounds, really shouldn't need it, you're at less than half the tow rating of your truck.
As the other guys said, slow it down a bit on the back roads, I have no problem towing a 7,000 pound+ trailer at 80 mph on the highway, but I stick to the speed limits on the curvy stuff.
