Why not have a word with someone who does it on a regular basis.
The best example I can think of is Loganair, who do the Glasgow - Barra schedule service in the DHC6 (twin otter).
I flew on the service about once a month for two years, and we often had to an instrument let down over the sea to land on the beach.
Minima's were quite strict and adhered to like glue, the pilots often stated that the biggest problem was spatial orientation when you broke out of cloud and still had a lot of sea in front of you.
That, in my opinion is the biggest single factor to bear in mind when doing a cloud break over sea as opposed to over land.
I'm sorry, I've lost touch with all the people I used to know in Loganair, but I'm pretty sure that their Ops are still based in Glasgow, and an internet search will get you a number.
They always were a very friendly and highly professional bunch, and I'm sure they'll do their best to help.