It depends where they are paralleled at. If you add a second bank somewhere at the back and wire it to the converter in the middle of the RV while the converter still has the original house battery in front as is, the converter can recharge both battery sets and you don't have to run wires all the way from one battery set in the back to the other battery in front or change the wires to the front set.
Don't forget the frame is likely the 'wire' for most of the negative paths so you mostly only need to run a positive wire any great distance.
Of course it will take longer for the converter to recharge more batteries. You can get more charging amps too if you want.
