Not exactly a tow bar but here's a picture of my old work vehicle, it was a fully 4x4 Ford transit and had a front tow bar mounting point for putting boats in and out of the water (Ex Police vehicle) and the removeable bar was about 1.5 metres long to keep the engine out of the water..... not much use to us so we put a vice on it instead!
To be honest it was quite handy..... except when you forgot about it and walked into it! also looking back its a wonder we never got arrested!! it eventually got stolen.