Photo taken by Anthony Dillon in February 2010
BH Photo #156545
A real possibility Tim.
I checked the SHAARD listings and found only a couple ponies documented, but none over Sugar. There used to be lots of truss bridges over that creek... thru and ponies. Only the Hays Bridge and this transplant survive.
There were a couple of pony bridges crossing Sugar Creek on roads 900N & 1000N. I remember these as a child when our family would go to Harlan cemetery. They were replaced long ago. I do not see them on your Hancock County list. I wonder if this bridge is one if them.