I think main point is to use something adequate to hold your rats and traps, and certainly you want something long enough to stick up above the water level at least a foot or so. Idea is that if water levels rise, you can still find your sets...and if things freeze over you can still find your sets. I like the lathes in the cattails and weedy areas where huts and runs get hit for sets. I like my stakes to stand out a little from the surroundings so that I can find them in the low light periods. I trap a lot of very private lakes though. I would keep things very low key in more public lakes though, and would probably lean toward more natural branch-type stakes to blend in better.
Jim-NE