I had hoped to get the tail to stick out behind him, but I figured it would be too heavy to just attach then end of the tail to the sweatshirt or the pants. We decided to safety-pin it in two places to the back of the sweatshirt.
Everyone was pleased with the end result. My nephew got a kick out of the ears and demonstrated how they flopped up and down. Just a little excited? I modified the ears, at his request, so they stood up straighter, rather than be quite so floppy. I can't wait to see him with the face makeup, too.