Meigs, I show that there was no Gaines Landing Rd on an old Confederate scout map that I have- there were, however, a series of secondary roads that lead to Gaines Landing and the one that may help you the most I believe is the one where it shows the Goodwin Plantation a few miles Southwest of Monticello. The roads are not labled but that is the only landmark near where you are describing and plus there seems to be a good number of streams near the area proving a good water source. I hope this helps some as well.