Great South Bay Swim #4, 7/17--and seeking opinions

Hey folk, Feeling overall pretty good about the training for this swim--completed 10,000 yards max swim a week ago yesterday and 5400 yesterday. Going to group LCM pool workout tomorrow--and after that, one more item: a half mile open water race Tues. evening. I've done these half mile races before--they're part of a series, and they're not too hard--it's out against a river current, back with the current, but I really don't feel it that much, just conscious of a slight bit more effort. Then the swim back is current assisted. I'm just wondering if it's maybe too close to the 5.4 mile swim (Friday). What kind of experience do you have in similar situations? I have a feeling once I start I'll want to push my pace--race adrenaline and all that--but I know that could cost me a few days later. Still, it's only a half mile.... Maybe one last short workout... And one more chance to work on open water skills (although the difference between a river and a tidal body of salt water is pretty huge, I noticed last year!) Thoughts?