I know of no man who has spent as much time as you have working afloat who functions well without the input of some coffee in his bag. If you can make it without coffee, some of the guys sharing that small boat with you won't be so inclined. There has to at all times be a supply of coffee on your vessel, so I don't think you need to add it to the bag. However, I'd have something that would hold some coffee.

Also, you've got pens, but what are you going to write on. The boat you work on has things you can adapt for functioning on the trip you contemplate in case something happens, such as an EMP event. You might take paper from the boat, maybe ripping out sheets from a log if you are without a pad. But some waterproof paper might be a good idea. If you plan on being in a small boat for a few days, there are plenty of things that could happen and leave you with nothing else to write on.