YES, YOU CAN! I'M LIVING PROOF!
I was an RC (PC-term for RA) last year, while I was still very active in my sorority. I know I was virtually let off the hook during finals, I had no real responsibilities other than damage control and making sure I was prepared for finals. The only real concern was with Recruitment. As a counselor, I could not pursue serious friendships with residents of my building, so it made knowing girls really well before recruitment somewhat difficult. There was some resentment on the part of other sisters because of this, and add that to the fact that I wasn't able to devote 100% of my free time to the house (try 90-95%). Either way, I don't regret doing it, living out of house can be hard, but if you're willing to make the effort, you can be just as involved as, if not more than, some of the members who live in-house.
For time...I probably had about 5 hrs/week (outside of Rush) to devote fully to RC time, which is considerably less than the amount of time I would have worked if I had a campus job.