For someone in a bad enough situation that they are willing to commit insurance fraud by faking a crash, it probably is a pretty good risk.
See this earlier comment for a link to data on small plane ditching: https://news.ycombinator.com/item?id=8957313
That said, insurance companies aren't stupid. Would they really let the person insure the plane for so much that it is better to lose it for insurance than to simply sell it?
These are not unsurvivable forces we're talking about.
For example, to ship a new Cirrus SR20 to Australia starts at $28,995 and you'll need to wait for factory reassembly and certification. To ferry the same aircraft costs $22,800.
I'd imagine a strong enough headwind would burn through your fuel pretty quickly.
Edit: This story is about someone flying from Hawaii to California where the flight ended up taking 4 hours longer than expected due to unexpected headwind. Luckily for him, he was in an airplane with extremely long range and had planned to fly directly to Oshkosh, WI! http://www.ez.org/t/cp34-p3