Butch, You'll be putting supplemental braking on this new toad, correct?
I'm wondering: Does the motorhome warning about drop adapters take in ALL towing, or is it aimed mostly at Trailers? I ask because trailers usually need 7-10% of their loaded weight on the Hitch Ball. A towbar, in contrast, applies more like a couple dozen pounds. I realize that accelerating and stopping also stress the hitch and a drop adapter changes the leverage on it. You won't have but so much acceleration, and a supplemental braking system will reduce the stopping force in the hitch area. Also, a towed car won't produce the bucking kind of action over bumps and dips that a trailer can.
In summary, I don't think it would be a problem to use enough drop to get into the towbar's leveling range if the car isn't overweight and you use supplemental braking.
But get a GOOD Drop Adapter like this 8" Roadmaster
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Not a cheapie like this
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This exact one might be OK but some don't have a corner gusset between drop and drawbar and they've been known to fail at that weld after a few thousand miles of use.
Let's see what other Sprinter owners say...