I wondered that too about impound. I'm not sure because I don't think I've ever seen then to sound tech on Saturday night (not that I paid that much attention), but it seems to me you shouldn't have to impound it until the night before. As for being out near the course I don't think you'd be breaking any rules, you can walk the whole thing if you want as far as I know. As long as you don't actually ride it you're fine.

There are phone numbers / emails on the contact page at their site, send them a message and see what they say.