Total existentialist. I think you are asking if he is one. I think so. His book The Stranger completely examines tenants of existentialism from start to finish. If social order, responsibility for actions, and influence from others are all lost according to existentialism, then Camus certainly is existentialist. He presents Meursault as one who detaches completely from society and family, but will still get his own immediate needs met. Meursault also cares nothing for the life he took, or the concept of repentance that the preacher so desperately tries to get him to have by the end of the book. His own life seems worth nothing to him.
Often people claim to be one thing but their actions demonstrate them to be another. Sure, he could have created a character and that's all, but authors' attitudes and beliefs come through in their writing... they can't help it. That's just my opinion, of course.