baby monitor questions

Hello. New mom of twins here and trying to figure out how to place the video monitors in the nursery. If I put it on one wall it is too far away, another, too close, on a shelf, too low. If I hook them high towards the ceiling it shows the best picture but it has an on/off switch which suggests to me that they should be turned off when not in use and so will not be able to be reached well. Also, the monitor has batteries and a plug... says don't overcharge, and don't leave the battery in for extended times of being plugged in so what do I do? Take the battery out during the night then replace it each morning? I can't  imagine that people do this everyday, but I don't know anyone with newborns or your children to ask... please share any advise or input you have. Thanks!