If self tying, i say in front. If you have someone tie you, behind your back; with ankles taped as well, behind the back is a little more difficult to get out of.
either way, try to tape the elbows as close together as possible. If in front, you may discover your teeth can no longer reach the tpe on your wrists (grin).
If you believe in yourself enough - nobody else will figure out you're faking it.
A lot of duct tape is actually rather easy to break. Some of the stronger kinds can be a little more challenging but you can most likely still break it if you really want whether your hands are taped in front or behind (see Youtube videos on this if you don't believe me). If you're taped to something it might hold.
My thought to add to your post...is what if Caylee was already strapped into the car seat, alive, while the duct tape was being administered? Just a thought...I have no proof.