I have a 2019 so the vent is at the bottom for the rear bags. Neither of the midship or rear bags are full yet and the ballast gauge will just randomly jump to 100%. I don't have an additional overflow on the midship bags either but plan to at some point when I'm not being lazy lol. My fill times can be 15-17 minutes, sometimes longer if I have to reset the ballast levels and then toggle the switches again. I have G6 ballast so it seems like 15 minutes is much longer fill times than it should be for adding an additional 880 lbs per twin ballast pumps. I think stock fill was 5-6 minutes for the 1,000 lb stock rear bag. My drain times for the rear are 12 minutes and they get completely drained but filling is taking much longer.