Sounds like the particular extender(s) you’ve used don’t agree with your scrotum.
My guess is that you’ll have to save up and go with a higher budget item to get something comfortable.
I, personally, have an X4 product. After using it for months, I was able to get to a point where I could tolerate up to 90minutes.
Ball burn is a problem, no matter what extender you get. The trick seems to be pulling the scrotum down, so less skin is inside the extender, chancing position when it becomes uncomfortable, and adding lubricant if needed.
For noose padding, I use and recommend ResQTape or a knockoff.
I put the noose as far to the end as I can. When I was doing less tension, I could secure it IN the sulcus under the glans. Now, at higher tension, I’m securing the noose at the same place as you’ve shown in the photos.
Try to extend for 2+ hours each day, broken up into shorter sessions. If you can manage 4 sessions a day that are 30min or longer each, you’ll see gains within 3-6 months.