If you're really looking for the slug way to do it just get some Rust-Oleum hi-temp bbq paint and spray directly over the rust. To hades with the prep and masking, whatever overspray gets on the rotor face will soon be polished off by the pads. No long term ill effects, maybe a few heavy grunting stops and then it's all back to business as usual. On occasion we get drums and rotors that are painted as a rust preventative during shipping. Only two alternatives - cut them on the lathe or smoke the paint off. Guess which way we prefer.
Give your most difficult jobs to the laziest worker - they will always figure out the easiest way to complete the task.