I don't see how the fuge would have any flow/turnover in any but the first one, am I missing something? The first one works for me, as ideally the skimmer should be before the fuge to avoid skimming out pods/beneficial organisms that would breed in it. As long as you have some sort of reliable auto top off, the small section could be used for the return, but otherwise the water level would fluctuate an awful lot. You may want to rearrange the baffles or at least add one at the bottom left of the middle section to contain a dsb.