There isn't anything a hitch would void unless you towed 5000lbs X-country with your RDX. You just have to decide if you want add an Acura hitch or go aftermarket. Aftermarket will be cheaper to purchase and install compared to the dealership. If you do go aftermarket, you can pick between 1.25 inch or 2 inch size receiver for the bike rack. This depends on what type of bike rack you pick. It can be a pain and an extra step to use an adapter if the rack doesn't match the receiver size.
I find platform racks are much easier to use and secure the bike better compared to hanging type hitch racks. Hanging bike racks are usually cheaper; but, it can take some prep work to secure on rack like raising the seat for a cross bar adapter for step thru bikes and strapping down to help with sway. Another issue I didn't like with my old Softride Dura 4 hanging racks was the bikes would sometimes drag on the ground over big bumps/dips. Never an issue with my Saris SuperClamp 4 platform rack.
Platform racks can be very expensive; but, are the easiest to use. 1Up platform rack can stay on the back of your RDX all year and can be locked in the up position when not in use. No issues interfering with back-up camera in lock up position; but, it might interfere with back up and cross traffic sensors.
The thing you have to think about with platform racks is how does the bike secure on the rack. Most platform rack can have tire tray straps and secure with two arms over each tire. Others have the same tire tray straps and have a center mounted arm that comes down on the upper crossbar. The center mounted arm might not work if your bike is a step-thru. The arm on the tire platform rack might not work if you bike depending on the fenders might be in the way.
You local bike shop can recommend a racks that best fits you RDX. Then you can check out 1.25 inch or 2" hitches that will fit that rack from Acura, U-Haul, or etrailer.com.
1UP USA builds the most durable, hassle-free hitch-mounting and bike-loading racks you’ll find—anywhere. Our unique “no hitch pin” design increases depth adjustability and reliably eliminates wobble and play to keep your bike(s) incredibly secure. Plus they attach and unattach to your vehicle in as
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Lowest Price Trailer Hitch Guarantee. Installation instructions and lifetime expert support on all purchases of 2020 Acura RDX Trailer Hitch. Order online at etrailer.com or call 800-298-1624.
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Old picture of my 08 RDX with etrailer 2 inch hitch and Saris SuperClamp rack (4" fat tire Radrover ebike and Radcity step-thru ebike):