Erm, see picture at left for an alternative approach to single engine over water.
Seriously though, whenever I've been in a floatplane there has never been any question of life jackets, rafts etc. I suppose the theory must be that you're going to be OK staying with the plane, even after it has capsized. But I've never been told this or seen it written down anywhere - do floatplanes ever sink after capsizing after ditching after engine failure?