The most frustrating thing about a hitch mounted bike rack is the fact they are rigid and it is virtually impossible to access the rear hatch of a camper, van, SUV, or hatchback with the bikes mounted. This is frustrating on a trip when you want to remove luggage, etc. and leave the bikes fixed in place. This modification allows the bikes to tilt while you open the hatch, then re-secure them in place. All without removing them.
Step 1: Safety
First, make certain you have a properly installed, frame mounted receiver style hitch that will support the rack. I bought a Sportwing bike rack with a 1,1/4" drawbar that fit my receiver. Before assembling it according to manufacturer's instructions, I made a new drawbar. I warn you this will violate the bike rack manufacturers warranty. Make sure you know how to weld, or get a certified welder to do it. Also, purchase proper hardened bolts and hitch pins.