I'm be nervous to leave the luggage all day at Pearl Harbor. There is crime everywhere, but we were warned repeatedly not to leave any valuables in the car in a public area, even in the trunk. This advice came from everyone from the valet, to the captain on an excursion, to the tourbooks we read.
It would involve extra driving, but I would rather leave the luggage secure at bell services at Disney and return early to get it before going to the airport.
Having something stolen from my rental, or having a window broken, on the day you are leaving would be a nightmare to me. We've heard that tourists are targeted in Hawaii more actively for theft because if you decide to press charges, you need to attend the court hearing. Since tourists generally don't want to return to the island to press charges, the thiefs are more brazen knowing that if they are caught they will probably not be charged. This may be an urban legend, but this has been relayed to us several times by different residents of the island.
That being said, we have had no problems with theft on any of our vacations to Hawaii. However, we never leave any valuables in the car, and always leave the doors unlocked. That way they won't need to break a window to take a look around, and I don't think the thiefs are looking to steal a car, probably more likely looking for a camera or GPS. Might be dumb to leave it unlocked, but at some of our hikes the parking lots have lots of shattered car window glass scattered around and I don't want to deal with the issue on a rental.