Sounds like you have the metal working figured out.
I'd suggest to keep your eyes out for new construction sites in your area, residential sites are the easiest to get close to. Stop and ask someone if you can pick up some scrap. Most crews are OK with it as long as you aren't in the way or doing gymnastics in the dumpster. Some guys want you to remove scrap as it is weight that they pay to dispose. It used to be that 15% of wood delivered to a typical home build gets cycled into a dumpster. That figure has dropped some but it's still a lot of waste. Lumber that has been kiln dried (everything from a construction site) can be legally transported and burned. Steer clear of treated or painted wood, it is not that wonderful for campfires.