I just repeat the imo simplest scenario one more time (slightly enhanced):
0) A single ill-intended/disgruntled/****ed-up Abductor/Tractorman waits for the right moment sitting in his/her car at the car park opposite of the OC entrance. See picture below for his viewpoint. It really is a perfect spot, although I would park my car slightly to the left from where the photo was taken so that he could even see who was entering/exiting the patio door that evening.
1) He sees the McCanns entering the OC ~20:30, but he cannot move yet since all other T9 friends are dripping in shortly after that. So, he decides to move after GM has done his checks and also finished his 3-minute chat with JW. He might even wait for JT to also come back and then make the move.
2) Fastest and safest way to get into 5A: up the stairs and through the unclosed patio door. Safest to close the door behind you to make things look normal from the outside (possibly even from the restaurant) and to avoid early detection when somebody checks in.
3) Safest way out and to get back to your car: via the front door (no key needed when opened from the inside, I guess, but always key needed when entering from the outside), no traces, turn left and go around the block. Pretty good shelter on that footpath covered by trees/plants and the least chance of bumping into anybody of the "T9-checkers" heads on. This route is supported by the freshest scent trace picked up 4 times by the sniffer dogs on May 4th and 8th and the trace was lost in the car park on all occasions (assuming the ground sniffing dogs also pick up scent even when a person is carried and little body particles land on the ground).
4) Open the window/shutter as a back-up escape plan to avoid ending up trapped in the children's room (or to stronger suggest a kidnap to damage the park's reputation). The escape plan was however not needed and it was save to leave via the front door. Hence an open window/shutter was left and therefore also no traces of burglary or lichen/sills damages were found. It leaves exactly the state that was observed by KM at 10PM who obviously immediately thought that the kidnapped her. Note: he picked Maddie and not one of the twins. Why? Maybe she might have woken up and make some noise when he opened the window/shutter too loudly, hence he grabbed her to minimize the risk of early detection and a potentially risky witness in hind sight.
5) He wore gloves, so no traces left (and if he did, they got polluted anyway by so many folk running around before 5A was properly sealed by PJ).
That's all you need.