I like that you are getting more feeling in your quads. Just make sure you are only doing this every other day so you have adequate rest between episodes of the squat
The hands elevated childs pose
You should feel pulling under the arm pit. This movement stretches your Lat and promotes thoracic ext mobility which most people like yourself are lacking. It can be difficult to coordinate thoracic ext with abdominal control…I will give you another option below in BOLD
I am going to start to incorporate some rotational movements to assess your ability to tolerate slow and controlled rotation prior to faster swing related movements
Over the ball hip ext or over the bed is fine…you could also lay over an ottoman
You can try some tennis which may be a nice precursor to the golf swing that puts a little more stress on the back