If it is your project, then you control your own hours. So it seems feasible, as long as you set good boundaries and stick to them. And as long as you can be productive and hit your own goals within the limits you set for yourself.
But don't get investors in the mix - then you have other people pushing you to hit their goals and deadlines, and it will go off the rails. So maybe the "startup" playbooks are not correct for you, but that doesn't mean you cannot do your own thing.
Basically, don't be a "founder". Be independent. Do your thing, your way. That is how most of the self-employed people that I know live their lives, anyway.
