Building Layout without actual Surveying Equipment

What will be the best way to get an actual measurement of the property line to the existin shed shown here. I did not have enough in the budget to bring back an acutal surveyor with a gps to take shots on the existing shed, but I figured if I found the iron pipe, I could run a string line from property corner to property corner and just measure off from the string line. But, the area is heavily forested along the property line, so now I'm not sure what to do. I have the topo in cad and have all the coordinates but just wanted to see if there were any other alternatives or measuring techniques I could use to obtain distances for the corners of the shed to the property line. Suggestions?