I'm not going to question the op
But I am going to express an opinion
Getting twice the storage amp hours does Not mean you are using twice as much
It does mean that if you are using 50% aka 115 amp hours
You will more only use 25% for the same 115 amp hours
This will extend battery life during your normal use, and give extra capacity when needed
If the present converter does an adequate job restoring 115 amp hours into two batteries, it should be ok for recharging 115 amp hrs back to four batteries
Yes if you use double that aka 50% of the bank of four, then it will take longer
And you may need a larger converter, if this is going to be a regular occurrence