Auto watering systems will not work well and will probably be more of a pain than a help with your current set up. You need to switch to a rack system with tubs that slide out from under their mesh. They are not hard to build. Mine cost around $120 US for a 6 tub rack with watering system hard line plumbed. The tubs are huge and easily house 3 females with their litters. One thing we have found is sisters tend to do better raising their young together than complete stranger rats if you just keep them together always.