Murphy sleeps in a crate, he goes in around 9 or 10pm and usually lasts until 5:30 or 6am. While I am at work I baby gate him in the kitchen with pp pads. He 9 times out of 10 hits the pad.
He is 6 months now, I got him at about 13 weeks.
8 weeks is pretty young and I don't have any experience with a puppy that little. Sounds like if she makes it through the night and it's only a couple of hours before your friend takes her out and then only a couple more before you get home, then that she may be okay, but I honestly don't know. Being so little her frequency may vary as she gets older and eats and drinks more. Hopefully someone will answer better for you. Congrats on your new addition.