As time went on and we loaded more and more crap into our 13' Burro
the bouncing got less and less.
I tie wrapped the curtain rods in place and bungied the closet door. Placed the long stuff on the bed and sort of locked everything together on the floor. That's were it all ended up anyway.
After that, only on roads with really bad plates, I 355 in Illinois, I 90 eastbound in Minnesota ( the worse ever) did the trailer go into oscillation. Now we have the 17' Burro
and so far I haven't noticed any bounce ( more room , more junk), but I haven't been on those roads yet either.