no trailer but i have strapped downa motorcyle in a open trailer with no bump to hold it to. justt strap all four corners down so it cant move forward OR backward. if you are really worried. nail a few stacked 2x4s down to the trailer floor and then push it against that and strap it down that way. ive done my yzf600 my vstar and a kawasucki cruiser this way on a open trailer with no issues.
mostt people use two maybe 3 straps... i am over kill and strap it from every where and use like 6 can never be too many straps