Not sure it’s a good idea to ‘store’ rice at room temperature, it’s a bacterial disaster according to many hygiene experts. Lots of good suggestions there though, living on tins, packets etc for two weeks wouldn’t hurt anyone - some do it all the time! I think you can get small electric cool boxes too. These can run off 24v when you are cruising and would help to keep milk, butter etc cool for a while. I know boaters who do that.