I think you'll be OK. I have held mine for 6 hours and it has been fine. I don't know that I would hold it much longer than that though.
My guess is that she'll see a rise up to 192-195 or so and then start to fall as the temp in the box lowers.
You could have her pull, double-foil, and then place in a cooler with some towels on top around 3:30-4:30 or so. Then it would have a 3-4 hour rest. Even after a 4 hour rest, it will be plenty warm for pulling and eating.