Yep you got to hit air books, (which is 99% of them) first. To me you're just better off going small on the bad line rather than trying to get big money on both sides.
You're best off going big on whatever line is off market price. If you can beat pinnaclesports take-back just once per day and bet just half Kelly, your bankroll will more than triple every single year. Start with $1000, turn it into $250,000 in five years. Bet full Kelly and you will be close to $1.4 million in five years starting with just $1000. Obviously you will run into limits very quickly, but even betting small markets at a good book, you will much closer to $1000 per week rather than $100. With the limits on major sports it should start getting close to $10,000 per week
If anyone is able to do it regularly, congratulations, you are well on your way to earning millions betting on sports. If you haven't yet earned your millions betting sports, it means you're not able to do this regularly.