Advice is usually free, good advice is priceless. I'll pass on the same advice I was given 23 years ago. Don't let yourself get pigeon holed into one industry. When that industry is down, and thats all you've ever done, it's hard to make the switch. I suggest stowing the level III plans until you have at least 10 years in, in a variety of industries and techniques. Learn to read the signal echo dynamics, not the machine. When all else fails, the echo dynamics will sheed the light on true or false calls. Aerospace/immersion is great experience, but can't stand the test of time for something that will carry you through in the lean times.
Diversity is key to all, take note of what happened to the boeing and other aerospace company Level III PT's or UT's after 911.
5 years in I thought I knew what I was doing, 10 years in I just knew I knew what I was doing, and 15 years in I actually did know what I was doing and enough to know there is always something new to learn.
An NDT inspector is a professional student and test taker. The day you sit back and say "I don't need anything else" education wise, you'd better get your application into McDonalds.
Did I mention diversity? that applies to other methods as well. One cert wonders don't last long.
Never pass up on any training in your chosen profession, and most training outside of it. The more you know the more your worth.
As for would the states recognize your certs, don't limit it to the states. Get prepared for the idea of world travel and portability for your certs. Study the various certification and reciprocity agreements currently in place and the trends thereof. Study multiple industry trends on top of that as they relate to your certs.
Over all, and above all, avoid that pigeon hole like the plague. It's kind of like being the Guru valve grinder in a shop, What happens to them when there is a shortage of valves to grind?
regards,
gerald