@Maxwell - bolt on rear hub is not feasible.
@AllenG - My rack is rated for 72 Kilos.
FWIW - I am using my rack to pick my son up from school/summer camp. He weighs ~45 pounds. Max distance we ride is <2 miles. Speed is < 10 mph. I just want something stationary to give him a break and to avoid the accidental shoe into the spokes.