Has the vet checked for Cushing's, WooKeef? That can also cause excess drinking/urination. Especially in an older dog, we like to rule out everything we can before deciding it's just a behavioral problem.
But if everything has been checked and physically she's fine, than rationing her water is a suitable solution. We have two dogs that can't make it through the night unless we cut off their water supply after 6:30 p.m. The other six have free access to the water but these two have been trained not go to the bowls once they've had their after-dinner drink. They do just fine all night without free access and aren't even particularly thirsty when they get up in the morning (at least, they don't make a beeline for the water bowls