I have done Network Engineering work through a small consulting firm billing out at the rates I mentioned (oh and I burnt out there big time btw) and on my own as an iOS developer as well. It's not for everyone and you have to understand that the work is not as much about the tech as it is customer service and keeping your clients happy. Go find someone who wants something built and has money to pay you to do it. Explain to them the time commitment you are able to provide them.
As for the the unsustainable culture you are building together with your founders :) One of the more successful people I know built a company working for days a week. I know full well the temptation to work insane hours all the time but the problem with that is when you really need to put in a large number of hours as happens from time to time there is nothing left in the tank.
I was wondering if someone can do Network engineering as a part-time gig? Obviously for small or medium sized businesses. I guess that depends if these businesses have enterprise grade equipment or not.
Plenty of firms large enough to require a solid network with maybe a few locations yet small enough where it does not make sense to hire someone full time. Small trading shops, hedge funds, financial advisors, VCs all come to mind.
As for the the unsustainable culture you are building together with your founders :) One of the more successful people I know built a company working for days a week. I know full well the temptation to work insane hours all the time but the problem with that is when you really need to put in a large number of hours as happens from time to time there is nothing left in the tank.