What half plausible story could you even offer for that damage under comprehensive?
You could claim that you took an off ramp too fast, but you're going to have to file an incident report with the police or state and lying on an official document in order to defraud the insurance company is like popping zits with a vice grip.
I seriously wondered about a compression fracture.
That or a crushed disk. Didn't Evel Knievel have a similar injury?
You think alcohol could possibly be involved?
It would be easier to identify the times/places where alcohol wasn't involved, I bet.