Lots? Well not really anymore. That might be an issue to get a good turnout and make it interesting. There's really only a few top busa car builders anymore (like some you named) that have quite a few cars out there already: King, Short, & Tom Pro. That's pretty much it. Sick Sand Travel, but they are no longer. Sonic, Sandbullet, and a bunch of some copy-cat builders that are either no longer or don't build enough cars or good enough cars to be recognized, IMO.
Yoshi definitely builds a badass car that looks like it works very well. Hopefully within the next year or so we start to see some of his cars in the dunes (at Dumont & Glamis) to see how well they work. It's always great seeing other competitive cars being built that work in the dunes.
All I know is I'd love to be right up there and ready to prove my car's abilities if such an event would take place. I am so happy with my new car. Hopefully SSC starts building more cars like my custom build. It does so damn well it's rediculous. yiah yiah