NB being drop in replacements for lead acid batteries will work with existing charger just check rates, one used recommended 4-16A charger. I'd still be incline to disconnect once charged.
As you point out the battery chosen should be capable of accepting the chargers maximum current delivery. There is a danger the battery might overheat if it is charged too quickly.
But once a battery has reached its full charge, the more modern battery chargers reduce their output from high or "Bulk" charging rates to a much lower "maintenance" rate usually limited by the chargers reduced output voltage.
The batteries 100% charged standing voltage is determined by the the type of chemistry in the battery and will be the same for any size of "12V" battery using that chemistry. Provided the charger can be configured for the type of battery chemistry, there should be no reason to disconnect the battery once it has reached full charge.
But equally there is no harm in disconnecting, except it might be forgotten, or disconnected at the wrong time leaving the battery with less charge than you think and it might not have enough charger to complete your manoeuvring when you want it.