In RV park. Now have car to drive. Disconnect RV battery?

A simple trickle charger will work but needs to be monitored and shut off when fully charged.
There are also trickle chargers with overcharge protection.
A smart charger is a better choice if it is to be left unattended for a longer period of time.
There are small solar, (relatively inexpensive) chargers that come with a controller, and in my opinion are a better investment. I would suggest one in the 40 watt range.
No matter which application is chosen, it is always advisable to monitor, and check water level.