Towing a boat - hitch options

[Dupersenior]

So, I originally bought my X5 in part because I wanted something that could tow my ski boat. I finally found one with all the options I was looking for, but it didn't come with a tow hitch. It seemed like the OEM tow hitch install was a pretty straightforward bolt-in procedure, so I didn't let that stop me and pulled the trigger. Now, unfortunately, there's a problem - there are no more OEM E53 X5 tow hitches available. I've heard that for whatever reason they aren't being made any more, and every dealer in North America is sold out of them.

My question is, what are the best options for getting my X5 to tow a boat? Does anyone have experience using an aftermarket hitch to tow a heavy (~3500 lb) trailer? I wouldn't be towing more than 10x per year, but the towing would involve long drives at highway speeds, and obviously negotiating a boat ramp for launch and return. So, not exactly light duty.

Lots of the aftermarket hitch kits are rated to 5k-6k lbs, but are they reliable for heavy use? I've heard people say that no aftermarket hitch is safe for towing a boat, but these are reputable companies, and my boat weighs way less than the max ratings.

Otherwise, anyone have clues where to find an OEM hitch?