Weird I just got "told" either here or on popup-portal the other day when I suggested a good "winter" minder type charger and he said the one built in to the camper is just fine, stick with that.
For me I don't want to "use" the onboard systems for that purpose and put hours of wear and tear on it. I would rather those hours come while its occupied
I have a ~$50 minder on mine with a "winter" mode.