Your ideas sound good to me... personally I'd even want to lock the 120V outlets, at least if US stage guys are as bad as European ones. I've worked with semiprofessional DJs and the like for a few times, and I always had to keep them from using their 230V extension cords! Each and every single one of them was a different violation! (usually: broken cord caps, poor strain relief, wrong type of cord or even solid wire cable used rather than stranded cord). My absolute favourite: the extension cord with two male cord caps to feed a homebrew light control box (read: wooden box with maybe a dozen switched receptacles, likely not in boxes rated for combustible surfaces).
