If you can cleanup and particularly brighten up the image that would help in identifying certain features in the picture.
Basically, the only two things you have to work with in approximating the date of this photo are the types of harnesses used on the horses and the buckboard itself. However, that will only give you when that type of equipment was in vogue and by the time this photo was taken that equipment could be very old. My guess is 1880s based only on the equipment.
Another possibility is to find someone who knows a lot about horses and can identify the breed. That might help to narrow down the location if a certain breed was very popular in a particular region.
Maybe you can put an approximate date to the picture by knowing what type of occupation uncle Jake had at any given time that would require him to use a horse-driven wagon to transport items under at white sheet.