Instead of just strapping more crap designed for something other than what you're using it for together, you could just step away from the carports altogether (well, keep 'em and demote them to a kitchen structure), and engineer something that's modular, scalable, sound, and has great bang for the buck. Look into EMT conduit frame structures. You can get fittings either locally in some towns or online, shade poles available cheap from nearly any hardware or building supply store on the planet (and easily cut to size), then just add tarps or shade cloth which you attach using ball bungees. Most common designs work in 10' square increments, with nearly limitless possibilities. Growing and changing from year to year becomes as simple as getting the additional fittings/conduit/tarp you'll need and making a bigger version, or on the flipside if you ever have a minimal year or want to do some smaller regional event, just bring the bits you need to make a smaller structure.