I don't think you are using the term crop factor correctly. When referring to "x", typically one is referring to zoom, more specifically the longest focal length divided by the shortest. So 70x means the longest focal length is 70 times longer the shortest. the crop factor when talking about dslr's refers to field of view relative to 35mm. Since DSLR's have a smaller sensor area than 35mm film, the same focal length will have a different field of view. Camcorders (and digital point and shoot cameras) can have larger "x" ratings because of their much smaller sensors. As you mention, "x" is a relatively useless term.
Now that being said, you can always crop your photo's to achieve a different filed of view/perspective. However, extreme cropping like your suggesting will lead to a serious reduction of quality. Which isn't all that different from using the extreme zoom on a camcorder, which usually results in extremely poor quality.