I don't think that attempting to maximize suffering is a good idea. If you go down that path, then finding creative ways to lawyer our way around "cruel and unusual" will become the name of the game (say for example, claiming that a plainly cruel punishment is acceptable so long as we do it a lot, making it not unusual. This has been argued before on HN...[0])
I honestly find the suggestion that we should use life imprisonment instead of execution because it is more cruel to be far more disturbing than suggestions that we should just use execution. You are proposing that we do something that you consider more cruel then execution... I'm not good with that.
