One Piece statues

I will be visiting Kumamoto in August, and was curious if anyone has some pro tips for traveling around to see all the One Piece statues? Apparently they are spaced out quite a bit, and several are difficult to get to via public transportation. I looked into a tour agency that offers to take you to them over the course of a day, but they are unavailable during the dates I'm visiting. Any and all help on this matter is truly appreciated!