I don't like the idea because then part of your water coming out of the tank will never see the skimmer, thus making your systam somewhat less effecent. I think t'ing off of the return is better as the water has a chance to see the skimmer (which IMO also helps oxygen exchange). And may I ask why the outlet of the skimmer couldn't go back into the intake section of the sump?? I think this would be easier and a better option as flowing it to the fuge will give some non controlable flow, and not all your water enters the skimmer which the nutrients from the water that does not would be good for the macros exspecially if you have a good skimmer that removes a lot of dark waste.