Yes, that's great, but I think in the long-term it would be super awesome to not have to spend so many extra hours, but to somehow get sponsored and to be able to reduce the "normal" work time for the company I'm working to for instance 60 or 70%. I guess that would be a huge win, as I also want to spend more time with my girlfriend and for other hobbies.

I'm doing it like you mentioned, that is spending at least 2 hours 4 to 5 days a week (or sometimes more if time permits) since the last 1,5 years and 5,5 years with breaks in-between. However, last year was pretty awesome, as the project now get's contributions at least weekly and I've found at least one member, who is consistently pushing the project :-)