My kid plans to never change his Florida residency as long as he stays active duty.
Especially considering state taxes at his current posting.
That's what I did. I was a New York resident when I went on active duty so I changed it to Florida and kept it there until I retired from the military. Since we got moved around from state to state so often it just made the most sense. I voted by absentee ballot in Florida every year but that was my only real connection to it.
They really made it very easy -- told me to just write in "Courthouse Precinct" for my address on the absentee ballot and they would accept it.