As mentioned, fords have a different overworld graphic tile, although I can't see any difference during the winter...
I generally settle outside of the cultural bubbles close to rapids (it sure is convenient to have easy access to water during the winter, and an escape route when hostile critters invade your turf (you need a paddle for that, plus a craft).
Note that sestas only work in shallow water, so you should be able to use a raft with a sesta to cross a ford without having to deal with the cold water (in summer the water temperature isn't a problem, so you should be able to wade across, even if you might get a little cold you'll heat up soon enough). A sesta won't get you across deep water, though.