Totally agree with the old-dude. I may be stating some obvious stuff here, but professional liability is the biggest hiccup. I believe it varies by state, but in these parts you are liable for your design for up to 12-14 years. If you haven't been covered by insurance continually during that period, you won't be protected. For example, if you design something in 2014, stop paying insurance from 2015-2016 and then get sued because your 2014 design fails in 2018, I don't think you'd be covered.
Even if you're practicing as a corporation/LLC, whatever, if you're not insured, the plaintiff can "pierce the corporate veil" and come after you.
Obviously, the odds of a lawsuit diminish as time goes on, and if you decide to close up shop, you can cover yourself with a cheaper policy-tail, but count on the insurance commitment as a long-term investment.
I like the old-dude's idea of joining forces with wifey to protect assets. However, I've only heard about that joint entity thing applying to protecting your home - I'm not sure if it would make you bullet-proof. I'd make a terribly lawyer though, and I can't wait to hear what others think about all of this.
Good luck in your decision!