There are a number of reasons why we sell our boards complete ready to ride. All other parts are purpose built. The danger is that a standard skate deck or unsuitable trucks will be used. The sales assistant will tell you that they are OK and although the board will function to a point there is a point where it will sketch out.
Problem is that usually happens at the worst possible time.
You should only use a purpose built dirt board for off road riding. Initially a lot of people have no conception of where a dirt board can be ridden. This is partly because they have no idea of the capacity of a dirt board and partly because they have never really looked at grass hills or other surfaces as potential riding terrain. The simple answer to this question is just about anywhere. That is not strictly true but there aren't many surfaces that can stop a dirt board other than loose sand.