Buying your son a place to live isn’t going to help you.
The parent primary residence needs to be in CA.
I believe it takes two years of residency to be considered an in state resident for tuition purposes.
If you have income below $80,000 a year…and think your second son might be Calgrant eligible…I believe you need to reside in the state for three years and your son would need to graduate from a CA high school.
When are you planning to move back to the states?
Sooner than later would be best.
If you are hoping to gain an edge in acceptance at say…UCLA or Berkeley…please know…these are highly competitive even for instate students.