The whole in-state versus out-of-state concept needs to change in my opinion. Why does it cost three times more to go to school if you are considered "out-of-state?" Instead of say 30k for a program you're paying 90k. That's 60k difference and more than three times what the national average is for a undergrad degree (~20k.) Assuming 20k is spent for undergrad and spending 90k for a graduate program the total is 110k. Add the fact you can't work for 3 years and that total is probably more like 130k. Take this into consideration and the fact that the national average for Physicians which is ~140k, I see a problem. Just a simple rant and nothing more. I'll probably still be paying my loan off when I'm 50+ lol.
To answer your question, I don't know of any loopholes. For the institutions I'm looking at, there are some pretty strict requirements. I have to live and work in a state for a year without being physically in classes. Even if I do this, it is still up to someone's judgement to whether or not I will be granted "in-state" vs "out-of-state" tuition. I may have no choice but to bite the bullet and take the "out-of-state" rate if I want to go to the school of my choice. To pick another school would basically me saying goodbye to my girlfriend and family for three years (probably saying goodbye to my girlfriend for good at least at the relationship level). Definitely a stressful process. So this is the price of attaining the DPT, at least from my perspective. I'd rather eat the financial expense than the personal expense though so I'll most likely bury myself in student loan debt. The price of doing what I feel I'm meant to do. Hopefully this helped a little.
I've never heard of this occurring. I think it's more common for other grad schools such as vet school to do this because there isn't a school in every state. There are at least a few PT schools in every state so I couldn't see them giving OS waivers. But it never hurts to ask the schools themselves and make sure!