I need a decent SUV towing rig that won't leave me stranded on the side of the road with grapes that need to be crushed.
The towing capacity of the LR4 (5.0 V8) is ~7,700 pounds. More than your Q7 but not quite at the upper end of your target range. And as for not leaving you stranded...at least you'll have very comfy seats and an excellent stereo to help pass the time.
Then there's always this, which will crush your grapes for you as you are driving west on I-90.