Of course, I am anti-DP, but I do have this to say about your argument:
1) In the two "extremes" you give, you are far more towards the former than the middle. Televised executions? Dungeons and an expanded DP? Man, I wouldn't want to live in a state where you're governor.
2) Doing hard hard time is not going to make anybody think twice about committing crime. Hell, DP didn't make anybody think twice about committing crime. No matter how harsh the punishment, most people do not expect to be caught.
3) You seem to ignore Life Meaning Life in your list of choices, which would certainly help dealings with retrials down the line after new evidence has been found.
4) You seem to ignore mistrials and biased judges, courts, juries. Bobby Seale, 1971, for example.