The usual exceptions to the IRA early withdrawal penalties seem to be rather limited. Some of them are only available in specific circumstances such as the owner's death. The only one that seems to be allowable for any IRA investor and for any purpose is SEPP which looks rather restrictive in terms of the amount withdrawn and the time period.
Is it practical to use a Roth conversion to withdraw money early with no penalty? From what I read it seems like this could work. You would of course pay income tax on the conversion, but you'd have to pay it anyway at the time of withdrawal. From my understanding of the withdrawal rules you would have to wait 5 years after the conversion, but the withdrawals are considered as being of a favorable order (first contributions and then the earliest conversion) so it wouldn't be a problem if you had also made some direct Roth contributions earlier that you could live off for 5 years.