I too would recommend Gasoline,, A Yahama EF-2400I exceeds your requirements.
And this puppy is so "Loud" you may well not even hear it running less the A/C kicks in.
True story: Rally, so there is considerable crowd noise.. Two generators runing a EF-1200i and an EF-2400i.. I could feel the exhaust from the 1200, and hear the 2400.. The man beside me could not hear either one. Neither could the salesman .. we did not have to raise our voices.. Till he loaded the 2400 down, Then it spoke up a bit.. Got about as loud as a Genrac 1000 traditional (But enclosed) generator.