Can only speak from our experience... when leaving to cruise
last year we installed a spectra, and the lowest draw 12V unit possible as our goal was to never have to run the genset.
We also upgraded to LifePo batteries
, and our plan works mostly... We probably run the genset every week or two to ensure top off, and we’ll probably add more solar that make even that unnecessary.
BUT - In reality, even if not needed to top off... the genset (like everything else onboard) should be used every week or two simply to exercise it, and if I had it to do over again would probably get a high flow 110V unit that would make 40-100 gallons in an hour of genset time vs us having to runt the watermaker
for 6-16 hours to accomplish the same thing.
Especially now as we look into the possibility of other “large” draws onboard like a washing
machine- we could likely time and use all of the above at once while exercising the genset.