It's a fine idea if you can give up the other nest space.
I don't leave my food and water past sundown... rats are chick predators and I try not to attract them EXTRA. They are here. And they have been known on this forum to have eaten hens alive!
I personally unblock the nest when she is ready to take them off. She usually works her way towards my pop door that has about a 6 inch lip on both sides, slightly more than some of the boxes height. Sometimes it takes the ladies a few days to get all the kids out the door here and make it into the covered run and usually pasture the following day, depending on weather. Ones hen wrangled 9 chicks and never left one behind. While others may struggle with 4. 1 is the worst to me though. It's pretty amazing to see them pulling feed out of the feeder they can't reach and dropping for the babes! Other flock mates will take advantage and try to push her off treats she finds and calls the babies to. It really frustrates me. But as long as it's just standard flock dynamics then everything is fine they are learning pecking order and how to avoid the higher ups... though I wish they would give hard working mom a break.
This year I have suffered heavy predation for the first time in 8 years of chickens, on my broody babies. After losing 3 babes on separate occasions from 2 separate broody's to a hawk, I confiscated the rest and put them under cover.

They were adopted and supposed to be next years breeding stock. Funds invest including how much they had grown so far was about an $8 a day snack for a raptor in the beautiful Pacific Northwest with plenty of other natural food resources available. I couldn't afford to take any larger hit.

Even my own eggs don't hatch for free. And as a lover of wildlife, I like to try and let them stay wild... which does NOT include opening a buffet at my place for ANY species other than the ones I raise. I won't eradicate rodents since I don't use poison. I collect my feed, try to be waste free with feed (almost impossible with chicks), and I trap/dispatch what I can.
Can't wait to see her bring her chicks out! Have you candled at all? How many are waiting on?

Guess it get's me excited.