You can buy adapters for bike racks that hold standard bike frames to allow them to carry full suspension bikes or ladies lame frames. I have one for my 80 dollar POS Target hitch rack. I bought the adapter at Sports Authority since I have a full suspension MTN bike. It is a bar that stretches out with clips at each end. It hooks onto the seat post and handle bar stem. It kinda sketches me out since I imagine the seat post sliding out. I use bungies for extra security. I think the bar was 20 dollars.
Most of the bike racks that suspend the bikes do not hold full suspension bikes with out an adapter.
One time I was pulled over and the cop told me he could ticket me for my bicycles blocking the view from the license plate. They can pull you over if this occurs and give you a ticket. Another issue is locking the bicycles. The rack you linked to does not mention if there is a lock. My cheapo rack does not lock, but I have a loops on my hitch and a cord to lock the bicycles up. Rear racks are easy to steal from.
IT AINT EAZY BEIN STEEZY