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.
Step 2: Start The Hack
You'll need 1,1/4" steel tube the same length as the supplied drawbar, some plate steel, and angle iron. Make a new mounting plate the same as the original. Drill it with the same size holes. Cut two pieces of the angle iron about 2" longer than the mounting plate and weld them to it so the steel tube fits between them and the iron has a 1" overhang at each end of the mounting plate. See the picture, the top drawbar is the supplied original. The bottom is the hack.
Step 3: Drill
Fit the new mounting plate over the end of the tube and try tilting it till it stops at the angle you want. You'll have to slide it back and forth so don't be in a hurry to drill. When you have it right, drill in 3 places. Near the rear of the plate at a point where you get the proper tilt angle,near the front of the plate for the securing pin and at the other end of the tube. (This is for the hitch mount.) use a drill size that will accommodate your supplied hitch pin.