Looked at various options, never pulled the trigger. Motorcycle dash cams would work well as they have to be waterproof. The Vantrue F1 was my favourite option, around £250 on Amazon. But do be aware that there might be lag issues, the camera telling you you are further away than you currently are.
Steve Saunders also indicated he might be developing an option, but that was a year ago or so, and nothing heard since then.
