20 weeks isn't drastic, no, but I could certainly design a better 20-weeker than just test and boldenone. I don't know your history, obviously, but if your sort of a newbie (which the test 500 range suggests), and this is one of your first shows, why not go at it clean?
Put together a SOLID PCT plan, keep training like a mutha, tighten the diet and cardio, and you shouldn't lose too much.