Have only towed the travel trailer a couple times, and she is only about 6 months old, and the hitch receiver is already getting some rust on the inside. Was thinking maybe getting the plastic Toyota insert and rubbing some lube on there before inserting? (inb4 jokes). Or is there a waterproof lube I could rub on there every once in a while that will stay protecting it from rust and won't wash/dry out in the elements?