I would say yes you need a wheel chock for the front wheel one on the back would be nice but you can do with out.
After setting your "Canyon Dancer" or handlebar straps the bike can not fall over left or right, the wheel chock stops the wheel from moving left or right on the bumps---Wheel chock means something (2x4) on both sides of the wheel touching the wheel and high enough that the wheel can not jump over it ..if the front wheel is not touching the trailer then you should put a a stop In front-----
On the rear I have found a strap over the passenger section of the seat (with a towel or what ever to protect it) will hold the back down very well.. You ca put a strap wrapped around the rear wheel if you want instead of over the top.. That's about it except set your rear parking break and tie your front break leaver in.
Again, not to tight on the front end tie downs (what ever you use) just a little compression of the forks is all it takes your holding the bike upright, the trailer has shocks the bike has shocks it's not about to fly out of the trailer.
I am sure there are other ways and better ways, this has worked for me over many thousands of trailing miles .
