I've found that you can constantly find a used listing for a quality 4 bike carrier until the week you really want to own one. Add to the angst many bike rack makers tell you not to use their carrier on the back of any trailer or towed vehicle. Of course, you see Jeeps towed with bikes on the back all the time, but there's probably some liability issue they would rather avoid. After reading many reviews on Amazon, I pulled the trigger on a Hollywood Racks HR1400
Sport Rider 4 bike rack, 4 bike capacity bike racks, hitch rack, bicycle carriers - Hollywood Racks
Amazon was priced about $399 with 2 day Prime shipping. Had 150+ reviews and a rating of 4.5 stars. I have bikes on it now with wheels from 24 to 29" without a problem.
A few notable pros and cons, mainly for talking points.
With the family I have an assortment of bikes in sizes and shapes. The hanging racks always look haphazard to me, this seems to be a nice clean way to carry an assortment of bikes.
This is built as a 2 bike carrier + a 2 bike extension.
It fits my 2014 Berkshire with zero hitch extension required* * I did turn one set of handlebars 90 deg to clear the radiator door.
It can also tilt up and lock vertical on the Berkshire when not in use. I do think I'd run a bungee on it to keep it from hitting radiator doors on a hard bounce.
Seems strong and stable, as per the reviews. Has a hitch anti-rattle system built in, and they also include a 7' locking bike cable keyed the same ss the provided locking hitch pin.
Built stout, therefore heavy. nearly 90# before you put a bike on it. As per other reviews, tilting this down for tailgate access with bikes on would be a 2 person job if managed to do it.
Steel racks tend to rust, so a can of Krylon will stay close for touch ups.
For carbon fiber frames, a rack that only holds bike by wheel (wheel clamp vs. frame clamp) is preferred. Not an issue for our camp bikes so I didn't let that be the deal breaker.
I have only had it on the Berkshire for 1100 miles, but the bikes were easy to secure and seemed to travel well. I did hit "that dip" on I-20 at a bridge on the west side Jackson MS that provided a test for catastrophic failure.
Anyway, it's bolted on and a keeper so here are a few pics. I'll try it out on the Jeep when I get home.
PICS: The angles are a little misleading but the bikes are not extending beyond the width of the RV on either side.