That will be very hard to do if it can be done at all.  To go that kind of distance you normal use directional antennas.  I don't know of any omni directionals that will give you that kind of range.  It might be that you could use directional antennas with overlapping signals on the base end, but you will still have problems on the rover coming back in.

Your best bet for Internet access would be either Sprint or Verizon broadband if they are available in your area.  You could get file access by using a VPN over Internet.