X2 on expanding chocks popping out. I didn't have X chock but a similar style and they spit out very easily. They helped stabilize and minimize movement of the TT but I would never trust them if there possibility of going down a hill existed.
There is only one answer if the possibility of it rolling on it's own exists and that is chaining through the wheels etc. No matter what style of chock or block, if it could be bumped and then move on its own, it needs to be chained. Other than that always keep a video cam handy so we have continuous YouTube material.
