!6 ga is pretty good unless it needs to be super strong for integral chassis stiffening or roll cage work.
I guess your going to "patch" up the holes. If they are small enough you can always "plug" weld them and save yourself some sheet metal. I'm also starting a winter body project on my mk3 chassis.
Glen Quagmire: Hello, 911? It's Quagmire. Yeah, it's caught in the window this time.
Social worker: "Glen honey, I got a question for you. What do you do for a living?
Quagmire: "I got a question for you. Why are you still here?"