No second person required.
Here's one i made earlier-http://twitpic.com/6yxfrohttp://twitpic.com/6yxftg
One of the links is a bit temperamental in Chrome, both seem to work fine in IE
Camping chair closed and stood up
Set up your kinect so your kneeling down, this allows you to get away with using a short fake person. Wrap the towel around the chair but don't let it drag. if it is stood at the right angle it will kinda look like its got 2 legs. balance the bin lid or something circular to look like a face on top on the towel facing kinect.
When you have done this move the fake person in front of kinect. If it doesn't register as a person at first adjust the head a bit, that was always the problem for me. Then move the fake person to the very right hand side of the screen until you get a green tick appear in the bottom right corner. You move to the left and mutate too and the achievement will pop.
Any other fake people setups please feel free to share!!
Any neg vote or suggestions please leave a comment