There is a kit available to do it, and I've seen one home built approach. I think its a bad idea. Last time I saw the homebuilt it was disasembled for modifications because the owner was not happy with how it worked.
Mounting the rack on the axle means adding a lot of weight, unsprung weight, that will not have a positive impact on handling and ride.
You'll also have a slip joint that has to work real well for this to work, and that slip joint will be in motion nearly all the time. If it sticks at all it will either break something or hamper suspension travel.
If the rack is not mounted on the axle I don't know how you could limit bump steer.
