Your obviousley going well prepared, but I think the most important piece of safety equipment for an extended over water crossing would be a HEED or Spare Air unit. All the SAR gear in the world won't help you if you don't get out of the aircraft alive!
A HEED 2 or HEED 3 system would suffice. It will give you about 30 secs of good air in a difficult situation.
Don't leave home without one
