I've got a 'Gadget towbar' fitted to mine and had to modify it slightly to fit around the vintage speed exhaust as otherwise the side bracket banged on the exhaust, just a bit of relieving on the side bracket was needed I'll try and find the pictures.
Out of interest I fitted one of the towbars from Bus OK recently with the removeable hitch and have to say it went on really well and is TUV approved, I'll be fitting more of those in the future, works out at about £300 for the bar and hitch but worked really well.