I completely sympathize with all of this. Roof rats are nasty shits. They were in my barn eating my chicken feed. We made a bucket trap and got rid of SO many, but really, you have to remove their food source if you can. And then start to seal up wherever they are nesting. We chose not to use rat poison, because we'd have so many dead bodies rotting, and that isn't good. We also have dogs who would kill and eat them, and we didn't want them to get sick. We had to use a combination of removing the food, removing the water... snap traps that we would move around (they are really smart about snap traps, or spring traps, whatever you call them).
In bucket traps, you need to use the tallest trash can you can find, because they can jump. And some people try to drown them, but rats can swim, so you really need to either take that trashcan somewhere and release them, or do something within that can to kill them, your choice. I personally used my dogs - sorry, not sorry.
Good luck, don't give up!