I am not by any means a pro or even mid to high stakes, but in the past when I was playing a lot, what I would do would be to set the level I was doing well at and establish the bankroll for that level, using the normal bankroll guidelines. Then anytime I had more than my bankroll I would cash out that portion. Back then Neteller
accepted US players and I would leave it there until I needed it, kinda like a savings. That little account helped me through a divorce and enabled me to cash my pro fighters purses on the road. I was also a boxing trainer back then.
If I wanted to move up a level I would keep the extra in my poker account until I my bankroll got big enough to play at a higher level. There is no way you can rely on paying the bills until you reach a high level and play consistently well. But you can make some extra money which helps. Another idea is just using your rakeback funds as spending money. That is taking for granted you are playing with enough bankroll to well insure you wont go bust through the downswings.