There are apparently ways to get instate tuition in Texas by the student owning property there (there are additional requirements but this is the most critical piece). For a family with substantial assets, helping the student to buy a condo there (in the student’s name) would be an option worth investigating.
We were deluged with flyers from realtors offering to help with these transactions when D18 was admitted to UT Austin (though we didn’t pursue it because she had already been offered one of the ultra-rare OOS tuition waivers and eventually went elsewhere with a full ride scholarship).