A very good drill for you would be to hit shots with a ball under the outside edge of your right foot (or a 2/4 or similar) and focus on maintaining the flex in your right knee.
You will get a good sense for how flexible you are or aren't very quickly and this will likely be a help to maintaining your spine angle and head position. Drill this with a heavy club/two clubs held together and with your eyes closed and hold your finish to check your balance. This will help show if your setup posture/clubfitting is out of alignment quite quickly because you won't be able to hold your finish in balance.
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"Support the On Plane Swinging Force in Balance"
"we have no friends, we have no enemies, we have only teachers"
Simplicity buffs, see 5-0, 1-L, 2-0 A and B 10-2-B, 4-D, 6B-1D, 6-B-3-0-1, 6-C-1, 6-E-2