CanAm told me that the Mercedes factory receiver on my 2007 ML320 CDI diesel (which had been re-welded by a factory recall in 2008) needed to be reinforced to properly handle the torque that is applied to the vehicle with weight distribution hitches.
There is a photo of what they did in my "images" link below the avatar. They had to drop the air tank for the air suspension and re install it below their bar.
The ML towed a new empty 2013 25FB International Serenity to Phoenix from Los Angles and crossed the CAT scales with only me in the car and got passing numbers on the axle and GVW loads. There was adequate power for the climb out of Palm Springs on I-10 east bound. The 833 pound Airstream literature tongue weight was 1,150 pounds with the Hensley hitch attached and full propane tanks.
The wife and I loaded the trailer with our "stuff" and both of us went to the CAT scales again. The car was not as happy with the trailer weighing 6,800 pounds and the axle ratings and GVW of the ML were exceeded. Being new to the whole towing scene, I found a 2012 Ram 2500HD with Cummins and the weight issues were solved.
I went to get the 23D on the East coast and towed it back to Phoenix with the ML. I stopped by CanAm to have them go over the Hensley hitch installation (same one as used on the 25FB) and they tack welded the lift arm brackets to the trailer frame. After a stop at A&P Vintage Trailer Works in Paradise, TX for some modifications, I towed the trailer on to Phoenix through some steep mountain descents into the Salt River Canyon south of Show Low, AZ.
Driving the posted 35 mph, the small diesel had enough back pressure to control the speed downhill without the brakes.
I think the ML and the 23D are a good match. I would not desire to tow our 31' Classic with my ML.
A more modestly sized Airstream should be no issue if the X-5 is setup properly and towed at reasonable speeds on the flats and significantly reduced speeds during mountain descents.
The ML has a front axle load bias (little payload even empty) with no one in the car, so adjusting for that to keep from exceeding the front GAWR can be a challenge. I would think that would also be the case for the X-5 since the diesel engine is heavier than their gasoline power plants.
The CAT scales will let the X-5 owner know if his numbers are appropriate. If so, then we all hope the welded supports in both the ML and the X-5 do their job properly with no hidden damge to the cars.
WBCCI Life Member 5123, AIR 70341, 4CU, WD9EMC
TV - 2012 Dodge 2500 4x4 Cummins HO, automatic, Centramatics, Kelderman level ride airbag suspension, bed shell
2014 31' Classic model 30 twin beds, 50 amp service, 900 watt solar system, Centramatics, Dill TPMS, disc brakes, 16" tires & wheels