Call Randy at BESTCONVERTERs or order just the PD9245 converter/charger unit from AMAZON... Not familar with what 120VAC and 12VDC Power Dist Panels comes with the PD9130. If it is just a couple of AC breakers and two or three 12VDC fuses you might want to consider getting a larger Power Distibution Panel setup with your converter/charger upgrade.
Mine is setup where I can have one full size main 120VAC beaker and 8 physical smaller half size slot breakers along with 11 each 12VDc Fuse positions. This may be the reason PD brought up the issue of staying with same as installed.
Your 120VAC/12VDC power Distribution Panel may be a stand alone thing and the converter/charger will be a deck mount version model.
If you want to add more batteries and want to re-charge then in a quick 3 hour time frame you will need to have a charger with the capacity of supplying 14.4VDC @ 17A-20A of DC Current Capacity for each battery in the battery bank. 45Amps for two batteries 90Amps for four batteries etc...
Roy Ken