It's not very clear from your message that you are getting OOM "just" by installing the Hawaii airports, or if you get them ONLY when you GO to one of them.
If you are getting OOMs outside the area of the Hawaiian airports, then it's 100% their installation doesn't have anything to do with the errors because, as explained many times already when OOMs are discussed, all our sceneries do NOT waste ANY memory if you are flying outside their ranges, which usually from 8 to 15 NM outside the airport center.
Since we handle loading of the objects in a custom way, we are not relying on the memory management made by the sim, so you can be sure that all memory needed by the scenery is reclaimed when you exit from its area.