Roger, et al …
First – confirm that you have adequate tongue weight
. US experts seem to say 'at least 10 percent' of the gross weight
of the trailer should be on the hitch. I agree more with those who suggest that 12 to 15 percent is a better target.
As you would expect that up and down jerking motion is amplified by the weight
of the trailer in relation to the tow vehicle. It makes sense that a light
tow vehicle would feel the effect of the movements from a heaver trailer.
The older concrete highways with tar strips almost caused me to stop traveling when towing my Scamp
19' 5vr. Then I starting using a Shocker Air Hitch and could forget the Scamp
was there while driving over most any surface. Now that I tow a Casita
17' with the same tow vehicle, the Shocker is probably not necessary but since I have it – I use it. It is a little pricey and probably not for everybody but if you really want to isolate the trailer from the tow vehicle – it does work. (Disclaimer: I have no interest in Shocker other than as a satisfied customer.)