If you company doesn't require seals or locks it doesn't mean that you can't put your own on there.
loads whether it was required or not. You can buy your own seals from the truck stop.
Make sure you don't have to have the doors open when you leave the shipper for security to check at the gate if there is one.
It was comforting to know for certain that no one had been in the trailer after parking someone where for extended time.
Of course, being a city driver, I don't know if you leave the truck like that. You may be with the truck all of the time. If that is so you are able to monitor the trailer by default.