If you're maxed in 401k and Roth in target funds, then you already have self balancing funds - they adjust the ratio of stocks to bonds as you get closer to the target date.
And as you're not sure what exactly you'll be doing with the money, and you don't see yourself stopping either of your other jobs, I'd go for option A - set it up in the total stock market index fund and forget about it for the most part. Revisit a few times a year just to say "hi" to your growing amount, and ponder what you want to do with yourself.
Don't know how old you are, but might want to figure out some life goals - work at both jobs for as long as it's enjoyable is cool, but you're bound to have something else in a bucket list (travel, write, go back to school, learn a certain skill or take up a nifty new hobby) and don't write off the idea of having a family any time soon - life has a funny way of throwing curve balls. :)