A few thoughts:
1) Try to get accepted at the cheapest school. $30k vs. $60k is huge. If you only have to pay $30k for this, that's ideal.
2) Practice living on just your wife's income. Use your income to pay down mortgage and save. Honestly, I'd probably just save and leave the PMI alone, but that's just me. Others with mortgages will likely chime in on this. To me, it seems like paying off Peter to just borrow more money from Peter later. If you can avoid taking out loans, or take out less in loans, that's ideal. Keep in mind that you don't just pay interest on student loans, you also pay an origination fee and maybe other fees, depending on the lender.
3) If there are any programs that would allow you to get a graduate assistantship or similar job, do it. Apply for scholarships, fellowships, anything to get extra funding for school.
4) If there is any way you could work even a few shifts per month while in school, do it. Sub, on-call, weekends, whatever. If that's not possible, do everything you can to be frugal in as many ways as you can think of: avoid eating out, cut all non-necessities, etc.
5) One other thought: make sure you aren't paying too much in income taxes. How will you know you're paying too much? If you get more in refunds than you have in credits. Adjust withholding for your wife's income when you quit your job--with only her income, your tax bill will be lower, and you can have more money in her checks each month. I recently realized this for me and my DH (he quit his job in the summer to do grad school full time), and it's been really helpful.