Unfortunately my husband and I have been experiencing the same problems for almost 3 years now.. And we have spent so much money on our truck and new WDH, 2 sway bars
.. in excess of $6K.. We also pulled a smaller TT for years.. never any problems.. Then bought a NEW Rockwood Ultra light, 26', weights about 6,000 #'s (dry weight).. other trailer weighed about 4,500.. so we thought, it has to be the truck! right? People told us it was the weight wasn't disturbed in the trailer correctly, your trucks tires aren't right and it just goes on and on.. all people just guessing at our expense..and every time still ended with same issue.
Then this last NOV while still under warranty we had an axle go bad.. they replaced.. however still the same problem!
We found out that the new trailer has independent suspension.. not advisable for a heavy trailer.. and it is all over the road, SCARY ALL OVER THE ROAD! This heavy of trailer should NOT have independent suspension it is all about a "safety" issue.. Our tires which might have possibly 8K miles are almost warn out..
I will be contacting the forest river warranty agent for this area soon.. I have had many problems in the past with this guy.. had to call channel 7 on your side to get issues resolved.. Good Luck..