Hello there, looking good and at the finish line👍
Firstly, if she's eating a tonne, then I would certainly match her needs and give her the 5+ liters of water if you think that will carry her longer. At this stage in the game, though, it's hard to keep up with them since they do eat so quickly and what you're doing daily still may be the best option. Even though they're drying quickly, you're avoiding water logging, which is perfect. This one is more your call then anything else. It is suggested to look for run-off, however, so we know we are washing out excess salts that may be sitting stagnant in our soil (I usually look for a bit more at this time 20-30% RO). So, I guess ya, up the feeding amount and ensure a good amount of RO.
Second part of the question pertaining to pistils and time to flush/chop: I just straight up say trichomes are where it's at when determining the right time to harvest and/or flush. Pistil hairs are good benchmarks to follow and can help you ballpark the point in time you may need to flush or chop. But pistil hairs can be inconsistent and not actually represent the stage of growth in the plant. Sometimes they brown out very early when the girl isn't ripe yet and visa versa, where new white pistils are being pushed but the girl is done and ready to chop. You have the magnifier👍 and from your picture's I see you're very, very close. Most trichs are starting to "cloud" and the clear trichs are becoming less in number quite quickly. Objective for optimal harvest is to aim for 100% cloudy trichomes (100% is impossible to get, but it's a 'goal' lol). When I start my flush (10-14 days before chop) is when I see about 70% cloudy trichs. After that 10-14 days the remaining 30% or trichs should have clouded out and you're in the harvest zone. You will still see some clear and even some amber trichs kicking around in there, but that's normal. If you're looking at 90% + cloudy, you've done a great job in estimating the harvest date👍
That's all I got! Throw me a PM if ever you need and we can shoot the poop further. And congrats on this beast. Happy smoke!