Sea specs in the US do prescription sunnies.
www.seaspecs.com/You may get a bit of distortion but it depends on your prescription.
They have a pretty quick turnaround time.
I bought some non-prescription seaspecs but could not find anyone locally who could/would put lenses in them so I went back to seaspecs and bought them from them.
I'm sure someone you know or sail with will have a pair of non-prescription ones so ask them if you can try them for size (and colour) before you order.
Hope this helps.