DS17 is going to go to an out of state university as well. We have researched all residency requirements, and here is our plan:
He will move the day he turns 18 (by choice lol...he has this great idea of spending the first half of his birthday at home with us as a "kid", and at 12noon (which is very close to the time he was born) he will leave for school as an adult. Lucky for him, his birthday is at the perfect time of the year to execute the plan lol)
He has a job lined up in the new state already. And it's a job that will teach him a skill and a lot of people make a career out of, so it won't be viewed as a "college" job (residency frowns on typical server, fast food, or retail jobs!)
He will move in with his Aunt/Godmother and start paying her rent, which he will get a receipt for each month. For the first year, he will attend a (really good, university-type setup) community college and work close to full-time. The following year, he will apply for his University of choice and begin there in the Physical Therapy program.
Basically, the residency requirements for this university state that they have to be living in the new state for at least 12 months, they cannot be living there SOLELY to attend a school, they cannot live with relatives for the sole purpose of attending school, and they must prove that they intend to stay in the state for more than just going to school. DS is ok with that as he misses his home state very much and has always intended to move back as soon as he could and live there forever.
We decided against DS17 applying for the University straight out of HS because they will deny him residency (of course) BUT when he applies again after 12 months, if he was denied once, they will really scrutinize everything. So we thought it was better for him to establish himself FIRST, then apply in a year.
I cannot pay $20,000 for out of state tuition for even one year, so instead of a gap year, he will get some of his basic classes out of the way and save up some serious cash. This is the best route for our family, and my awesome, sensible son is all for it.