I'm building the same T/A Mustang. Here's the roll cage that I built using Evergreen rod and tube. I used a roll cage from a NASCAR kit as a basic guide and built my cage on a jig, where I could bend and glue the tubes.
You should check this website out tells you all about air flow booth setup fans etc. He doesn't like bath fans either but still tons of great info about design.
I used this site when I built my paint booth, I did the cross vent design booth shown and used a squirrel cage fan to vent the fumes outside. It also has a furnace filter to catch the paint particles before venting fumes, lighting is a small florescent two tube fixture. The body of the booth is made of 1/2 inch plywood painted white. I built it with simple wood working tools, except for a table saw to cut the sheet of plywood into piece's. If I remember correctly, it was built, wired and painted in one day and in use a day later. Simple stuff.