My main issues with 12v is I may have to put my inverter like 6-7 cable feet away from the battery bank and at 12v and 3000watts I’m worried about that run at 4/0 getting hot/warm.
I used the OEM 4/0 wiring in my MotorHome to run my Multiplus 12/3000. It is at least 10 feet away - and maybe more - depends on how that wire was ran. I do have some voltage drop (more than I would like), but the 4/0 cables do not get warm - much less hot.
Your lithium cells can handle the inrush of the generator start - but will the two Bms’s be able to support the inrush? That is the research that needs done.And I also max out the mppt at 12v at 1400watts so I’m losing like 300 watts of production.
At 12v my main issues is the starting the onan generator. It pulls like 100 amps @ 12v so I may need to have a 12v battery anyway just to deal with that draw. How ever infrequent that is cause I think with 1700 watts of solar I may never need it.