Perhaps this is a spoiler, but that black tarry stuff wasn't coming up. I briefly considered using a portable torch, following the example of my grandfather when he was removing the linoleum from his kitchen floor. I was only a small fry, but it made an impression. And the black goo from that memory looks a lot like this stuff.
We did go on our Memorial Day camping trip. The roof was incomplete, but we brought the tarps along and hoped for a dry weekend. A lot more beer was going to be needed to complete this project.