Open Face, Piss Pot (safe?)

[Simon.Pieman]

Damaged c-spine or not, if they ain't breathing, they'll be dead in few minutes.

Not good advice, chest compression helps the heart move blood that has already been oxygenated by the lungs round to the brain and there's no telling how long this enriched blood lasts, it could be some time. Certainly people have been revived after many minutes of compression and no breaths given.
Best to keep compressions going until paramedics arrive and give a breath if you can, after every dozen or so compressions. And don't blame yourself if your arms cramp up and you have to give up.