You really haven't provided enough details to give a reasonably accurate answer. How many hours per day would you be playing? What kind of spread? What kind of games? Are just a few of the unanswered questions. If you are serious about blackjack advantage play, you will need to invest in a good simulator. I recommend
www.qfit.com You feed all your information in and will receive reasonable expectations.
In very generic terms, $200-$300 per day is $70,000 to $100,000 per year. Last year my results fell in the lower end of that range, spreading $25-$300, playing an estimated 98,000 hands which I would estimate to be about 1600 hours. (I don't really count time, I count hands) My results were pretty close to expectation. Most AP's would not find this to be a reasonable return for the time invested though and would opt for larger bet spreads and max bets over a shorter time to reach such expectations, but then you are getting into issues of heat and longevity, which you stated you wish to avoid. Hope this helps.