Due to owner knowing an inadequacy(in his view) tell owner to step up and trim the generator fee to compensate for his faulty(in his opinion) rental equipment.
Then try it both ways. It won't matter if the owner admits to the deficiency and mans up or not...you're test driving...do tests.
Then decide.
Your experience is the only opinion that carries any weight.
It's nice to ask opinions, it's required that you sort them as they'll suit you.
As far as extra fuel used.
Do the math and see how little it affects mpg. It's surprisingly little.
You Might come up with 120mpg to run that generator on YOUR RV when you buy one.
__________________
|