That is a Good question NMDriver. I have a 4000 watt, 2 piston Onan BFA. I can and do run it all day at times, but it's loud and a bit thirsty. Being able to run the fridge off batteries means only running the genny to power the microwave, electric coffee pot or A/C. I have done the whole cool the fridge then turn off and keep closed. That works for a day of travel, but then it takes a couple of hours to cool it back down for the overnight and you have to keep the generator running if you will be opening/closing the fridge for normal usage. If I am running the A/C I don't care about noise or gas usage. If I am in a quiet camp site or at an event (we use my RV as the check-in for paintball events), then noise is a concern and sitting outside the RV with the generator running means yelling back and forth. Also, the less gas I use in general (I only get 6-7 mpg for poops sake) the better. Having battery power available means a nice quiet, peaceful camping experience and running the genny for a couple hours in the morning is very doable as we have to cook and get the day started.
Ok, you have a different use you put your rig to.
I get along with my 3500w genny in the back of the truck and a 5 gal. can of gas.
