Just curious, where in WI are you located?
I'm a guy that ***** at finances, but I'll try to offer some advice. When I was out of college (2005) I splurged a bit thinking that things were on the up and up and that my career would be taking off. I bought a nice car and spent a good amount of money modifying it, while at the same time making payments on my $22k in student loans.
One thing I realized is that I stretched myself too thin to actually enjoy what I had. I was worrying about blowing my motor which I didn't have the money to rebuild, and I didn't want to pay to have the car shipped somewhere to get a better tune. I just didn't have much fun with the car because the stress and worrying got in the way. I ended up parting out the mods, selling the car, and using the money to pay off the last of my student loans. I was debt free for many years, well, before buying a house (currently my only debt).
With about 320k in debt, I would just slow down on your dreams of a shop right now. You have no clue what the future might bring, and given that the economy is on life support with (unprecedented) cheap money, you'll be thanking yourself in the future if times get tight and you don't have even more debt to pay off. I make about what your wife makes, and I have $135k to pay off on my house. That is the absolute max that I wanted to go, and often times wish I had got a place more in the $100k range (houses are much cheaper up here in GB compared to Madison, where I moved from 2 years ago).
How come you want a shop? Of course every guy does, but I'd be really happy with a 3 car with your first house - plenty of ways to allow you to accomplish what you want to accomplish in a dedicated shop.