"Overcharge" means too much voltage, not too many amps. Your alternator cannot do too much voltage. The battery itself has an amps "acceptance" limit for any particular state of charge and voltage. So no worries.
You do need to worry about ever getting that nice AGM fully recharged though. That means you need an ammeter to see when it gets down to nearly zip amps acceptance at its rated absorption voltage (14.8 or perhaps 14.4 depending on spec) with no load on it.
Arranging to be able to do that in an RV while camping is where it gets "interesting". Forum member Landyacht might have a few tips on that.
