The appropriate shop socket-type tools can be used with an impact gun. I doubt if you have a burly one (or one at all) but it is a thought. If you know a[n auto] mechanic, you may be able to convince them to use theirs for you...just make sure they know to run the tool in 'forward' position. Applying smooth force may restrict you to the above scenario of a 3 foot cheater.

Soak with kroil (available on Amazon), securely attach your removal tool with a bolt/washer, and ideally, have a box wrench that will fit it. A whack with a deadblow hammer will loosen most stuck parts.