Whats you're conclusion? I read your opinion on leaving free water in the cooler....so what do you do? Edit, Mogur/Mowgli...not the same person...sorry. Anyways the rest is still relevant.
I do pretty much what riverman does, half or one gallon bottles frozen then I line the bottom, load the cooler and fill with loose crushed ice.
If I had a large enough freezer I'd probably do the layer and fill with water, then freeze thing but I don't. That certainly makes the best use of space for ice, but still allows free water to mix between your items.
For everyone else,
All jokes asside, my guess as to GreenWalls revalation: He welds (fabric, welds, like his boats, what ever they're made out of) himself up some water tight bags, cut to fit inside his cooler, then fills and freezes them. Then he lines his cooler, possibly layering with these larger self contained blocks.
Thus maximizing ice content and minimizing free water in the cooler. Or he does the same basic scnerio with hard plastic, maybe even aluminum - since he's a guru. At any rate the idea is to retain the water with out free water cross contaminating cooler contents. I've seen some potable water containers that are thin and flat that would fit in my larger cooler. If I recall they are marketed for 4-wheelers/off roaders. They weren't cheap but I thought they'd be a great way to get a lot of ice into a cooler. If you could manufacture something that was tailrr made for a specific cooler you'd have the best of both worlds - the best ice retention, while preserveing separation between items.
Yesterday's gone on down the river and you can't get it back. - Agustus McCrae