Whether or not it helps with the tummy-wrinkles, I did learn a great little trick the other day with the Gemini that helps lock you into the right contact point in your hip pocket:
When you invert up and then put your outside leg over the pole, before you let go with your arms, pull up and pull your chest through from between your arms. When you let go, the pole is automatically in the hip pocket in the right place and you don’t have to re-lock your leg to make sure it’s in the knee pit to hold you up.
That trick might help with some amount of sliding down the pole when you’re getting into your Gemini. The sliding might be pulling the skin around in your hip pocket around and resulting in the wrinkles you don’t like.
Good luck!