Back when I was installing Generac systems, I would get the gas company to provide a 2 psi meter at the customer location in place of the existing 6-8" WC(Water Column)meter. The higher pressure allowed for a line as small as 1/2 copper run to the genset and attached to a secondary regulator adjusted for an output of 11" WC pressure. The generator has a demand regulator inside that will only flow when there is manifold vacuum. Of course, at the meter, a regulator set for the standard 6-8" WC pressure fed the rest of the home. ^_^
TDD