I have always run max pressure without any problems. Most folks are amazed what their rig actually weighs after completely rigged and stocked. Drop by a truck scale and have it weighed.
Heat build up from under inflation and sidewall flex kill trailer tires faster than tread wear. Load rating on the sidewall is rated relative to spec pressure. If you lower the pressure, you can't expect the tire to carry enough load safely. I would rather have the trailer tires properly supporting the load, rather than worrying about how the tire will wear long term.
"Hello, My name is Bill, and I'm a tackleholic"