Not sure what you mean by "safe?" Since you posted this on the weed forum, you seem to realize that most gardeners find this plant way too aggressive, a weed, formally designated as a noxious invasive in many areas.

Basically i wanted to know if it would spread underneath the trailer or only where it could get light. I've since decided against the idea jus cus i read sooo many posts as to how hard it is to kill if i ever wanna put something else there.

It took me six years to get rid of this plant in my garden. Every little piece of root will make a new plant, so if you DO decide to turf it, make sure to sift through and get all the bits of root.