With the modern high efficiency inverter/chargers now available the effeciency for all load ranges from zero on up is sufficiently good so as to be relatively negligible in terms of energy wastage. In fact, if one needs a shore charger
(ostensibly you do or else you wouldn't have the battery
bank to drive this thing) the technology called "bidirectional switching" is what makes inverter/chargers so good. If you need the charger
you almost get the inverter
function "for free" or vice-versa. Here we are considering the latest switch-mode technology in that charger-only switch mode units cost almost as much as an inverter/charger.
As mentioned before, a generator
is not needed for heavy intermittent loads or light continuous loads...that is what an inverter
is best doing. Save the generator
for heavy continuous loads where it is optimally loaded.