I'm not sure I'm doing this right. I want to write about what a character intends to do: "Susan just had to get out and move around, even if it meant falling even farther behind on her work! She would catch up later tonight, no matter how long she had to stay up." The bolded sentence is the one I'm unsure about. "Tonight" is correct from Susan's point of view, but since I'm writing in the past tense, I'm getting all tangled up in the syntax. Should I use "tonight" there, or some other construction?