bucking/chucking with a TT?

Bucking like you call it will happen on some awful roads. On normal roads, it's a poor setup. In many cases, it's caused by too little tongue weight, so the trailer and the tow vehicle end up bouncing separately causing the bucking effect. If you watch the trailer a bit in your side view mirror while towing, you'll see that the thing does quite a bit of moving up and down. That's normal if it's in concert with the movement of the car. You typically don't feel that movement in your own vehicle because of the suspension, but watch another car in the lane beside you while driving and you'll see just how much movement happens. The tires and shocks absorb much of it.