I wouldn't strap a 50 dollar bike to the back ladder let alone a 5 thousand dollar one. The ladder on the back of any trailer, 5er or travel trailer is like the end of the line on the old "crack the whip" kids use to play. The lateral "G" force on any small move left or right in & out of traffic at 65mph is huge. Also the up & down "G" force going over bridge "expansion" joints on about 75% of every interstate bridge is the same. I have thought how is the 5er still hooked up after crossing some bridge expansion joints and that is just behind in the bed of the truck, not 43 feet behind the hitch..
Make sure your insurance is up to date....