Nice weather for sailing.....
Seriously, in practical terms, over that distance I would say just put on an immersion suit and have a PLB/Epirb (water activated?). You have no chance without either if you go down without comms. Surviving cold shock and your location/situation being known are key. And I would be very careful about the wx and vis... losing your horizon half way across would be my biggest concern... stay in the air.... no AH no go....?
Nose clips... in practical terms thats not quite right, cold shock stops you breathing for a few moments, a life jacket floats you facing the waves and wind so you need a pull down visor for surviving long exposure.. you would need to be wearing your nose clip on impact for it to be of use underwater... so would you be putting it on during a ditching..? would it stay on?
Also.. another tidbit... 150N life jackets don't hold a fully clothed male adult's face clear of the wave action.. you need 175 or 200/250N... 150 will be tiring while you wait... a pulldown visor is the most important feature of a life jacket though as the waves land on your belly and shoot up into your mouth channelled by the jacket itself. You can drown in the jacket once exhausted.. but with a visor you can have a nap... and I like napping..
