Hi Skyland
Your question regarding how to stretch or open your hips for more external rotation is basically the same question you have been asking in other posts: my answer will be the same, so I refer you back to those
threads.
My only other suggestion for you is to spend a bit of time and go see a physical therapist. You have reached the limits of what internet discussions can do to help you. You need one-on-one guidance with someone who can see your body. A therapist will be able to “scour” your hips to determine how much range of motion you have in the hips. Scouring will take your hips to the bone-on-bone edge, but it is not painful or harmful. Once you know where your bony stops are, you will know what your ultimate range of motion will be. It is possible that tension will stop her from getting to your compression edge, but this is the best way for you to know without getting X-rays of your hips.
Cheers
Bernie