Thanks for the feedback. I have used it once so far and it worked like a champ. No problems at all brewing outside.
I found what is called a "Starting Collar" in the roof venting section of Home Depot. This specific one was 8" and seemed the perfect size in both diameter and height. I think it's a Master Flow SCF8. It has a bunch of tabs which I bent to help get into position. I then used the same tabs to attach it to the bar that the burner is also attached to. I had to drill two holes for attaching this collar and that was the hardest part. Some #8x1/2 sheet metal screws are holding this on perfectly.
A pair of tin snips made quick work of the notching required to go over the burner neck.
SCF8 at HomeDepot
It is galvanized steel but I don't really think that's of any concern. It hasn't even discolored from my last brew day. If I am not mistaken, you need to be careful welding on galvanized steel because the vapor is harmful. I'm getting nowhere near welding temps during my boil.