You still need to show ID though and you can bet HMRC, Vosa and the environment agency will be looking for patterns. The best way to do it is to go legit with it. If you're in business chances are you'll occasionally carry rubbish so you should have a waste licence anyway. As for the yards not paying cash I think the government have got the public on side on this one after all the scrap metal thefts and a few overpaid plumbers moaning about the loss of a perk is not going to hold much sway.
It's happened, it's staying, live with it.