I have two comfortable set ups for my hanging BTC.
One is at my computer area, similar to what you are doing but I put my feet on the corner of the computer desk and have the chair moved back so I am lying down horizontal. Heat pad on the groin and good to go.
My second set up is downstairs at my weight bench. With the barbell across the post, I slide the bench back so I can lay down with a couple pillows under my head and set my ankles up and over the barbell.
This is my fav but I have to run an extension cord across the room to hook up the heat pad... also because I am horizontal and my thighs are straight up vertical it makes for a really small area of contact for the heat pad in the groin area.... so I normally just wrap with a blanket to keep things warm.
Good luck,