20mgs should be good, and take an extra with you if you feel like you need more. I wouldn't top 40mgs if I were you, and I think 30mgs is the top dose you would enjoy, but try the 20mgs first and see how it goes.
Stay hydrated and don't drink any alcohol on it. Also, I've never heard of the 36mg adderall, but if I had to guess I would say they are Concerta which you don't want to be taking for a rave.