First you need to determine if your RV has a built-in converter/charger that makes 12v when plugged into shore power or when a generator is running.
If it DOES, then that is probably the best way to get the battery charged up initially; then you can use the external charger you have to KEEP it charged when not being used.
Even though your charger says it is not for "large" batteries, it probably will work IF you leave it connected long enough......like maybe a couple of WEEKS.
Hopefully someone familiar with your model of RV can be more specific.