3 plumbers, 3 different statements on code. Can i get a sanity check?

Location: Houston/Harris County within city limits and in a MUD

I am looking to extend my gas line to the backyard for a portable generator. This would seem like a pretty straight forward thing to do in Houston, but i have had 3 plumbers over and each has given me a different statement on what is code, what can be permitted, etc. I don't know who i can trust.

Here is what i believe code is, from looking at Harris county websites for gas line extensions:

• gas line extensions by a licensed master plumber
• portal gen has to be 5' from house, 3' from fence
• cannot use more than a 6' gas hose (quick connect)
• Galvanized steel is fine; black iron needs to be painted/sealed

Can i get a consensus on what i need to do to ensure i can get it permitted and it's done to code? Trying to do the right thing 🙂

Thanks!