Maybe not what you're looking for, but this year i think I'm going to try a thin insole stuffed into a wool sock for a water crossing type 'shoe' instead of the crocs. A pair of costco Merino blend socks, and the stock insoles out of a pair of size 13 Aku boots weighs 4.4oz.
I haven't tried it outside the house yet, but I'm thinking it'll provide enough protection from the rocks for river crossings, and would make a decent stalking sock if needed. Probably not ideal for spending hours in camp, especially if it's wet or snowy, though I'll usually just put my boots on if I've got a lot of walking to do.
