i'd offer payment terms to the owner if i couldn't afford to pay lump sum; surest way to maintain peace of mind (for my son especially).
We heard back from the church and they are collecting more info and hopefully they will be able to cover it. Either way, we will do what we can to make it right. If the church insurance covers, we will make an additional donation (that will be payed for by son doing work). If not, we will try to come to an agreement for what both parties feel is fair for us to pay. Hopefully it doesn't come to that.
If the church, on their own, denies any liability w/o consulting with their carrier, make sure ask them to give their carrier info to the vehicle owner so they can file a claim and let the carrier decide coverage. IOW, the church doesn't have the final say on whether they are liable or not, their carrier does.
Bottom line: Your son crashed into someone's car so you're liable for all of the damages. I can't believe you are nitpicking the factors. This is your Church community, do you really want to act like a weasel? Man up, pay up. And punish your son however you deem necessary, that's your business.
Sounds like your son has a little motivation for a start-up lawn mowing company. Pony up man, your son is an extention of you, thus you are responsible. Don't be that guy.
