There is however another issue of just charging your batteries from the 50% charge to the 90% charge. You can do this charge state cycle for 12-14 times without doing damage to the batteries. After that you need to do a 100% charge state which will take the 12 hours or so of running the generator. Once you get a good 100% charge state then you can go back and start doing the 50%-90% charge state cycles again...
Our camping off the power grid is usually not longer than a week or so and we will do the 50% to 90% charging each morning around 8AM during breakfast. This is when we make our grind and brew coffee for the day with our Cuisinart Coffee maker when the generator is running. This only takes around five minutes to brew up a 10-cup pot of coffee into a thermos carafe.
Then by the time we do this routine for about a week we head for the house and this is when get to do the 12 hour or so full charge state. 12 hours is just too long for us to run our 2KW generator out in the field. The 2kw Honda Generator only has a 6-7 hour run on one tank of fuel. Also many places we go to here on the East side of the US doesn't allow that much continuous generator run time anyway. Better to do that long run at home off of shore power...
It is very routine for us now camping off the power grid...
Roy Ken