The official line is that the maximum portfolio size for the SO strategies is $100K. And I agree with this. (I've traded with much higher than this in 2020, but that was only possible due to the very high vol.)
So, a portfolio of $500K trading in calendars/straddles will be a problem.
Also, pls be careful if you require trading to provide an income to feed the family. It's possible to have a couple of losing months (see the Performance table on this site) and then our fear kicks in, and that can affect our trading ability. Trading with 'scared money' is a different game, in my experience.
Finally, if you are thinking of getting into trading the SO strategies again, I suggest starting with $10K, then each month, increasing this amount, as you build experience.
Good luck!