Ok, I figured out a way to get just enough corruption by the time of the theater scene. The cheerleader route gives a few more opportunities to get a bit more corruption here and there. Then when I got to the theater I said I probably would have preferred the superhero movie (+ 3 corruption) and brushed him away (+ 3 corruption, although it seemed a bit out of character for what I was going for) which seemed to be just enough to get the hand job scene (leaning into him gives a huge minus on corruption, making the hand job scene almost impossible to get if you've avoided Matt).
So, if you want to manually change it I can recommend you use this: https://f95zone.to/threads/renpy-save-editor-v1-6-1-last-moment.6456/
Its pretty user friendly and all of that and I find it easier to use if Im not going to fuck up stuff like variables. So, cash, corruption and grades (not sure about this one) should be fine.
You just have to load an existant save and search for what you need, save it on the program and after that load that save that you edited. For cash need to have gotten paid at least once before editting it, since it wont appear first.