I use the towing hitch on my SR+ almost every week for either trips to the local tip or longer jaunts picking up various items from Ebay etc, sometimes requiring a charge to get home.
One long trip was picking up a bulky object and with man maths I assumed there was plenty of charge to reach home after a rushed top up on a 50kW "Rapid" but as soon as I pulled away the "computer said no" and I stopped off for another top up at an SC closer to home.
It turned out that I did have plenty left at the end so the computer was just playing safe.
Range is hit a bit but not too much as you drive slower. Power though is barely affected and you can still burn away from a standstill!
To me it has paid for itself many times over.