There have been YC companies in the past that spent most of their time away from San Francisco, including some companies that actually spent most of their time in Europe. AirBnB famously flew to and from New York every week. You don't have to be there for the entire 3 months, although I think all that travel will likely exhaust you if you aren't absolutely committed to your company (and it sounds like it could be difficult with the baby).

Also, $80k for 3% is a far better equity proposal than YC. $80k for 5% would be equivalent. That said, I can't imagine they'd splinter themselves any further. I think the way they've set themselves up works great for them, obviously they can't please everyone.

If you really have that much interest for your idea, get several LOI (letter of intent) notices from your potential customers and take it to investors. That should get you a lot more than $80k.