According to Indianafiretowers.com.  In the 1930s, this area in Martin County was being called the White River Land Utilization Project as a project between the USDA Soil Conversation Service and the Indiana Department of Conservation. This area in Martin County becomes a naval ammunition facility as WW2 begins.

The southern Crane tower is the only one that seems to have a name (or two.) Indian Springs and Trinity Springs are both town names near the southern tower. I think both of these names have been applied to this southern tower. There is an NGS mark named INDIAN SPRINGS LOOKOUT TOWER (JA1932) referring to the southern-most of the Crane towers. I think this is fairly solid evidence that the southern tower was primarily named Indian Springs.

The name “Trinity Springs” is mentioned in the text on a USDA flyer about Hickory Ridge Lookout Tower: “The CCC camp, located in Kurtz, not only built the lookout tower at Hickory Ridge and Dutch Ridge, but also one at Trinity Springs.”

I have not see any names associated with the other three towers.