I have flown there quite a few times and per say i don`t have problem with water crossings. I used to send mine up to kirkwall. But they have wick, landholm and kirkwall and loads of fields to play with so plenty of escape options.
I might also add i worked on the islands for years and the wx forcast isn`t the best in the world. So to be honest never mind post ppl more like post instrument training be it imc or ir would be sensible.