There is one surefire way, don't work. Does your wife really need to earn that $15k? Particularly if its going to cost you a few thousand, why earn the money in the first place?
If she's obligated to work, maybe she can negotiate with her boss and reduce wages in exchange for 100% health coverage while she works. That gives you less taxable income and less premiums to pay.
MAGI is tricky. It's different for nearly every issue.