Right, forgot the timeline we were talking about happened after Neelix left.
But even without him, you don't need to resort to holograms. Voyager functions like a small village. People help each other out. In the cases where Tom and B'elana are both on duty at the same time, they'd leave her with somebody who isn't. Sam Wildman didn't leave her role in the ship: Naomi was raised by the community.