You need a pressure safety valve set at 10 bar, this is the only way to measure the pressure when using Trev's pressure regulator. You will also need different fittings and tube for sure. It looks from the picture that your fittings push into the tube. They won't hold 10 bar! Which by the way is still a lot of pressure. And yes you can leave the top open with a bungee return. Look through liftoffs build diary you'll learn a lot from Chris.