Most of the times I have a reflective vest in my backpack as well, especially when I know I will hitchhike in the dark. Once, about two years ago, I stood in the dark on a motorway access road in Belgium. I stood there for about an hour and luckily a women stopped and took me along to the next petrol station. Most people just tooted. Since then I take a vest along, even you are a good hitchhiker, you can never know where you end up. The reflective vest is really cheap and very tiny and lightly, so it does not disturb in your travel gear. In most European countries it is by law to have one like this in your car.