What should a electric pallet jack operator install to support a semi trailor that is not coupled to a tractor to prevent from upending?

An electric pallet jack operator should install wheel chocks behind the trailer's wheels to prevent it from rolling or upending. Additionally, using a stabilizing device or jack stands can help secure the trailer in place. It's important to ensure the trailer is on a level surface to minimize the risk of tipping. Always follow safety protocols when working with trailers.