
This is a product from RoadMaster called QuietHitch. BlueOx has something also.

The BlueOx is interesting because it squeezes slack both top-to-bottom and side-to-side.
When I was looking for Track Bars, I ended up in a conversation with Eric Davis. Eric owns Eric's RV and you might know his name from the Davis Track Bar for the fronts of Class A RVs. He was really helpful and also addressed how slack in the tow rig can cause the toad to bump steer the back of the RV. He said that there should be less than 1/2" total "give" between RV receiver and toad tow bar. If you use a "drop adapter" like pictured, or a "drop ball mount" it'll call for a device like QuietHitch.
Eric's remark didn't surprise me because I'd used those rental-type towbars that pull tight with chains. The slightest looseness and that towed vehicle would go absolutely nuts.