For continuity of evidence, I do not believe anything at all was done to the trailer while it was in Hamilton. Gibson sealed the doors and put a padlock on the back door. They towed it to Hamilton. AND WAITED FOR THE WARRANTS. They would have not have unsealed the trailer and gained access UNTIL they had authorization to do so. Once they got the warrants, presumably the Monday the 13th, Officer Laura Troubridge headed to the secure facility in Hamilton and drove behind the tow truck that was taking it to Tillsonburg where they were going to process the truck and trailer (2 different warrants) for evidence. The fact that there was a police presence at the location in Hamilton was likely (MOO) to keep the scene secure and so they could testify that it would have been impossible for an unknown subject to plant evidence/etc.
Do we know if the police stayed overnight?