If you know the highway names in Hawaii, you'll never get lost. For those of us who go by numbers, though - it's pretty scary . . . Like Alaska, this represents a compromise between systems - all the more important in Hawaii, where a stretch of road can change name or number at a moment's notice. They also use a rainbow on their license plates, to their credit.
Color is good.
I took half the rainbow and big black numbers off the license plate. I added the highway name in a smaller font underneath, since CCS mentioned the local importance of the road names. In my opinion, Hawaii has the worst shape of any state for the state outline method, followed closely by Rhode Island. It might be possible for each island to have its own shield, based on the island's shape. He was to Hawaii as George Washington was to Virginia.