<outside halo around the driver area>
I haven't seen your idea on the outside halo, but have you thought about bending up a structural roof rack? That's basically what I did on mine. I really like the looks of it so far
If you tie the cage to the frame, like I did, I'd leave *some space around the cage/ body for flex. Don't design the cage too tight to the windshield & think you can get your welder around every corner
Can't wait to see some more progress pics!