Grand Canyon guides have some cool ways to make the ice last. Here is a list of things they do: 1)pre-cool - as you did. Some even make friends with someone with a walk-in freezer, flood the cooler 1/4 full and freeze a solid clear block in the bottom which they then cover with cardboard. Waterproofed food goes on top of that, then cut pieces of Reflectix that match the interior dimension of the coolers top, edges are sealed with gorilla tape. This silver insert is then the seal at the top of the cooler - the first thing you see when you open it. The silver seal can then be used to shade the coolers interior when you are accessing contents when the sun is up. Always best to crack it in the shade or when the sun is down. Some folks are particular about always shading their cooler interiors. Good idea. (2) the first thing to lay on top of the sealed cooler is a piece of wet burlap, double thickness is better. They keep this wet all the time. Evaporative cooling technology. (3) on top of the wet burlap they place a paco pad for further insulation and comfort of passengers. Also, about the ice. If freezing water in the cooler is not possible, taking 1 gallon jugs of water and freezing them at home in the freezer is a great way to go. Clear frozen water melts much slower than commercial blocks and when it is in the plastic jugs it just becomes delightfully cold drinking water and you have no nasty juice in the bottom of your cooler to dig through. Tidy!

What length is your boat? Thinking about buying my first large raft and really appreciate your experience videos!