Try a 3/8" 10mm impact socket. It's six-sided and won't flex at all rounding off the bolt head. Use extensions as needed to put the ratchet where you can get it to turn.

Soak everything down with PB Blaster and give it time to work.

Remove right front wheel for much better access to the upper hidden bolt.

Cross your fingers that you don't shear any off. They aren't very large diameter bolts.