[threpwood]

If it is an open trailer, use a car cover so people can't see that it's a box (don't use factory car cover with big Porsche logo).

Locking the trailer to the jeep with multiple chains and paddle locks should be more than sufficient to secure your baby.

And, get a wireless spy camera with lcd monitor, so you can check it once in a while (hopefully your room is within line of sight of the camera as the signal can get weaken).

If it's not sufficient, disconnet batteries of your jeep, chain the steering down, and remove one of the tire with jack on!