That is nothing short of unsafe staffing, and YOUR license is at risk! Don't accept excuses from administration---if you continue to put up with these working conditions, they'll have absolutely no reason to change them. And if your facility is like mine (and just about every other nursing facility in this country nowadays), the top dogs are far more worried about their bottom line than they are about patient care. So you have to set some limits.
First of all, you need to think about how this workload places your patients in jeopardy. There is no way on earth one nurse can care adequately for that many people, even if they all are relatively stable. You've got people on vents; what happens when you're down the hall dealing with some crisis, your CNA is in another room, and one of them crashes?! Guess who's going to be held liable? Yes, the facility will be responsible for poor staffing, but YOU will also pay, big time, because you accepted this assignment, knowing staffing levels were unsafe.
The best thing you could possible do for yourself and your pts. is to tell management, in no uncertain terms, that you must have another nurse, and no fewer than four CNAs, on 3-11. Give them a deadline--say, 30 days--and if they tell you "we're working on it", or that they can't afford it, get yourself the hell out of there, and then call your state surveyors, senior services, or whoever monitors facilities in your area and report these unsafe conditions. Your patients' lives, and your sanity as well, may depend on it!!