First, congratulations! You are off to a great start with that amount of savings that young. If you can avoid lifestyle creep, you'll be ready to FIRE before you know it. A few suggestions from someone a little further down the road:
1. You are right to be thinking about minimizing your downside risks, but not necessarily about what you're focusing on to do so. Do you have disability insurance? What about life insurance, particularly when you have kids? What is the job market like in MI where you intend to move to -- are there multiple companies where you two could get comparable jobs if the first ones don't work out? If you build a plan around making over $200K, you are vulnerable in the short-term to losing the jobs you need to achieve that plan. (AMHIK) What kind of EF do you plan to maintain to tide you over in the event of a job loss?
2. I would encourage you to think not just about the different boxes to check -- paid off house, post-tax investments, etc. -- but also about the optimal time to check them. For example: I firmly agree that you want to go into FIRE with a paid-off house, because it lowers your monthly nut and thus gives you more flexibility in the face of temporary challenges. But there is much less benefit to paying off the house before you FIRE; the house will appreciate the same amount regardless of whether you have 1% equity or 99% equity, and if you can't make the payments, the bank will be more than happy to foreclose in either scenario. OTOH, the power of compounding means that the most valuable dollar you have to invest is the one you are investing today. So the optimal path is to focus now on tax-sheltered investments, and then as you get closer to FIRE, shift as needed to getting the house paid off.
3. Don't worry right now about having "too much" in a tax-sheltered plan; really, if that's the worst problem you have, you're golden. The reality is that unless you plan to work for 20-30 years, for most people tax-sheltered investments alone will not be enough to get you where you want to be when you want to be there. So it is very, very likely that by the time you are ready to FIRE, you will already have built up a pot of taxable investments you can access. But even if not, that is a worry for your final years before you FIRE. Really all you need is enough to get you through the first five years while you start the Roth conversions -- and if you've maintained a solid emergency fund, that alone will get you through a good chunk of that.
4. Your biggest risk, other than dramatic injury/illness or job loss, is lifestyle creep. This tends to happen fairly invisibly, particularly when you add kids to the equation. You'll need to watch out for that -- but you should also re-evaluate your priorities as your life changes. Once you have kids, you may decide it's worth working a few years longer in order to pay for college or some medical treatment they need; or you may decide that no lifestyle is worth spending more time apart from your kids and it's time to FIRE ASAP. So maintain your humility, continue to think about the life you really want to lead as a family, and maintain your flexibility. The good news is that a MMM-style lifestyle with low fixed expenses puts you in a great position to make those adjustments, no matter what you choose.
Good luck!