We used to have an HD Ultra and a Heritage Softail that we hauled all over the place. Just bought some very good ratchets and straps rated for 3k. Tied the front of the bikes to the D-rings in the trailer floor and the back to the D-rings in the back. Also used the soft tie down straps HD sells and tied from the frame and engine guards in front pulling the bike to the front and compressing the forks. Put the straps through the rear wheels and pulled the bike to the rear. Tightening the straps was just tight at the rear and then the front alternating left and right in order to keep the bike sitting level. Once the front was tight only a little take up was possible at the rear. No chocks needed.
We hauled this way for thousands of miles on terrible roads in the northeast and nothing ever moved. We now have a trike and same method works perfectly.