Hi Icecream44,
I currently do 3/4 Philosophy (have the exam tomorrow actually) and I was in a similar situation to you, where philosophy was one of my favourite subjects in year 11, but I had a clash going into year 12. What I did was do 3/4 Philosophy through the Distance Education Centre Victoria (DECV), where you complete the subject in your own time and you are in contact with your teachers through email and calling. Generally the DECV is for people who can't do subjects at their own school but they are happy to take in anyone.
The way it works is you are given course booklets which contain all of the theory you need to know for both units, and you complete a standard level of work and submit it weekly, where feedback is given. For SACs, you generally sit them at school under the supervision of a VCE coordinator.