If your batteries and charging system are in good shape they shouldn't need water very often. I've never heard of an automated system, but I don't think it should be necessary anyway. Besides, you should fill with distilled water if/when they need any.
My opinion as well, though I got tremendous service out of a set of US Battery L16's too.
And yes, Trojan and others make watering systems. My various banks of batteries all had very easy access so I just used one of those semi-automatic
push down pitchers, cut to the appropriate length (the Rolls had a much deeper "topping point" than the others.
As to water systems, I use a filler jug like the one below. Just push it into the cell and it fills to the proper level and shuts off. You don’t have to be able to see into the cell, just reach it with the jug. Got mine on Amazon, where else???
Golf Cart / Deep Cycle Battery Jug Water Filler Bottle w/ Auto Shut Off
If you're not over charging the batteries shouldn't need topping off very often. If they're hard to get to, an auto filling system helps a lot. You don't even need to see the batteries to use it. I use Flow-Rite, a local company here in Grand Rapids, MI. Check out flow-rite.com. Not affiliated, I just try to buy local.