Welcome to the forum Gazzacub,
Speaking as someone who has kicked people out of dumpsters, the best way to go is to set up your own play area on your own property. Dumpsters, compactors and dust bins are private property, no matter what country you call home. When you play in them you are trespassing and will be arrested if caught.
Dumpsters can contain dangerous material. Even a restaurant throws away more than food, broken glass from table ware and light fixtures, and chemicals are common. Also, the business isn’t the only one using their dumpster, other people get rid if things they can’t put in their own trash, like car parts and construction materials. Play safe.