You are correct. The purple wire is used for the reverse lights which many trailers are not equipped with.
If the trailer you are towing does not have reverse lights, the purple wire can just be capped off and secured out of the way. view full answer...
The torque specs for the Draw-Tite trailer hitch receiver, part # 75579, can be found in the install details that I've linked to this page for you. I've also linked an install video for you.
If you need replacement hardware use part # RHK and enter the hitch's manufacturer and part number and you will be ordering the original hardware included with the hitch. view full answer...
To install the Tow Ready T-One Wiring Harness, part # 118490, on your 2010 Volkswagen Routan you will plug the T-One connectors into the back of your tail light connectors. The T-One connector with the yellow wire will plug into the back of the tail lights on the drivers side and the T-One connector with the green wire will plug into the back of the tail lights on the passenger side.
The separate white wire will need to be grounded to a good, clean piece of metal like the vehicle frame.... view full answer...
The etrailer Trailer Hitch Receiver - Custom Fit - Matte Black Finish - Class III - 2" # e98854 torque specs are listed correctly. The verbiage for the bolt switches to thread diameter and not wrench size for torque values, so the larger bolt will be the 86 lbs you referenced and the smaller diameter bolt will be the 48 ft lbs you also referenced. I reached out to our tech to confirm so you can rest assured this is the correct fit. view full answer...
In order to use the reverse lights on your trailer, you will need to add a 4-Way to 5-Way adapter like # 47515. Using a circuit tester, like # PTW2993, find the wire behind your taillight assembly that carries the reverse light signal. It will have a signal when the vehicle is in reverse. Make sure you have someone in the vehicle to help you and put the emergency brake on for added safety. After you have found the reverse light wire, you can connect it to the Adapter 4 Pole to 5 Pole Trailer... view full answer...