When looking at carrying a motorcycle on a bumper (front or rear), it's a good idea to run some calculations to see how the weight will be distributed. There's a fairly simple worksheet that you can find
here.The "460" in the first formula is the weight of the bumper carrier so you'll need to change this number to match the weight of your carrier. If doing the calculation for a front bumper just reverse front and rear in the worksheet.
I think it was Archimedes who said "give me a long enough level and I can move the world". So remember, even a small weight at sufficient distance from the axle can really mess up the loads on the other axle changing the handling characteristics of the vehicle.