Can you say what track? (name or location)? very few tracks allow enough straight-away to run far over 110 mph. I know, I've tracked my MS3 four times now and ran my prior Subaru on at least 20 track days.
Not to be morbid, but I think it would be VERY POSITIVE to post a link to the crash vid from the trailing car. Nobody that seriously thinks about tracking is going to change their mind. My goodness, there are hundreds (thousands) of track crash videos to deter those not willing to risk it all.
Was this a true race event (placed positions) or a timed lap (transponder) event? Lots of auto insurance policies still cover catastrophic damage at track events as long as they are not sanctioned race events. Most "track day" events can qualify as a kind of driver's ed, if you're not using a transponder and competing for best times.
I know this to be true because a good friend of mine totaled his Evo MR at Buttonwillow track in CA and it was completed covered by his Progressive Auto insurance co.