I know what you mean, but again, I never need that and the investment in tmux is to high for edge cases. Btw: Long running jobs are easy with a cron job:
echo "/path/to/long_process.sh" | at now + 1 minute
If you and your team is happy with tmux, that's fine! But doing more or less the same things with easy linux commands is – in my opinion – the better way.
echo "/path/to/long_process.sh" | at now + 1 minute