I towed my 8 year old last week using 2 29er inner tubes daisy-chained, one end around my waist the other around her stem. She couldn't stop giggling.
2 wasn't quite long enough (she had to ride beside not behind me), I'll try 3 next time.
@Camstyn you can remove any user's comments from your view by clicking their avatar and clicking ignore. If you refresh the page you'll see their posts are gone.
It's great for peace of mind, and life's too short to read things you don't want to.