A PLB might come in handy with the SAT phone.
A few MRE's or meals that don't require water for prep. Whenever we go out on any boat, we always have a small fishing kit with at least a couple of good hand-lines if we don't have poles.
My boat bag has a couple of thick books, a writing tablet, pens, and a deck of playing cards in it, inside 2 zip lock bags.
I always bring my cell charger in my travel bag, which goes with me everywhere. Be aware of what voltage and plug in's are available. I've a charger that works off a AA battery for my cell for emergency use.
Sunscreen, lip balm, Aloe, bug juice, a floppy hat and extra sun glasses are a part of my bag.

Due to a breakdown, 4 of us spent a unplanned full day and overnight on a very small island in Bahamas back when I was in college. We were out of water, bug repellent and sunscreen. I had a sandals, a tee shirt and shorts, as did my buddy, the 2 women were in bikini's with just towels for sun protection. Not the right things to have when on a open cockpit boat, with no way to get out of the sun. To put it simply, sun poisoning is not fun. We had not left a detailed plan, and our friends didn't bother to start the SAR when we did not return, as we often spent extra days island camping.