The opponent left the chalk on the table during his last shot. That's a foul. Ok, maybe the rules imply that if it doesn't alter the outcome of the shot or touch any moving balls, it's not, but you can claim he used it as a visual aid to help him aim his last shot. Take your ball in hand and get your legal hit on the one.
Well, assuming I can see the 12, I might try to tie it up into the 8 & 15. Even though you give up the table, if tied up well, you stand a chance of getting back to the table. You're likely going to give up the table (unless you are Houdini), so why not try to make sure you are going to get back to it?
If I absolutely have to attempt a shot on the 7, page 2 might be a path option.
I really like Jude's answer though. When all else fails... PUNT.
I think the cluster you make with your first option is too easy to break out with ball in hand and a table full of insurance shots. But then, I think this game is DOA no matter what you do.