The Nanny = imaginary. Utility worker = real person. So your theory is that the non-existent nanny told the worker to go pee in the woods to find the body after she what?!
The tests inside and outside the bag will show that the bag has been in that area since being placed there by Casey. The duct tape and various other pieces of evidence will show that Casey bound the child plus the bag then drove her in the trunk of her car to the location where she dumped the body.
The A fam suspicions are unfounded and ridiculous. With proof which ties items with Caylee's body to the inside of their house and was sufficient for an overall search warrant which declared their home a crime scene...they are doing nothing except trying to continue the charade of the fake nanny. The stranger theory can be proven to be completely false. They won't find any hair, fiber, fingerprints, dna, etc. to include a fake nanny kidnapper being responsible for this.