Forget 9/11.
Forget the Regs.
What were you doing up till now to hamper unauthorised use of your aircraft?
Relying on good will? Bwa ha ha ha.....
Can think of two aircraft "borrowed" without asking (and stacked) this year locally. Both covered on Prune.
Sure insurance might cover it. Will it cover the inconvenience of turning up at the airport to find your aircraft gone?