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.