IMO the genset box is perfect.
Does your inverter have plugs or hardwired ... the 120vac side?
If hardwired you can just get into the transfer relay and change a few things. The 10# that goes to the WFCO now swing it to the inverter feed (shore power) side; then run the output of the inverter to the wfco feed you just cut off. Cool thing us the genset feed (you find that in the 4x4 jbox and attach a tail) let's you power the inverter for quick charge. Turn off the WFCO breaker... keep it for spare. You will need to also take the AC feed (and maybe the microwave) from WFCO breaker and run to a shore power connection. I ran mine (ac) to a breaker in the pantry access compartment then forward to the transfer switch. Going to transfer switch feed only would save a wire run. I already had part of that done. All this in #10/2. I used flame proof and salvaged marine cables.
If it has plugs, you will only have to run #12 to outlets of your choice (new) and get shore power to the inverter and plug them in. You won't have to remove the AC (and possibly micro) from the PD,
The inverter I have has a transfer relay that when on shore it charges the batteries quickly or powers the WFCO PD panel when off the grid.
XLR Hyperlite 29HFS
Ram 2500 6.7L CTD
A Modder's work is never done!