Each of us has different needs, different sex dolls and different settings to suit our different families and furniture. I spent a while and a few different ropes and pulleys to find the one that suits me and the girl.
I use the double pulley system because it can be easily raised and lowered. The wire is 9 mm. I have found that smaller, thinner ropes tend to slip easily - this may be different from others. 9mm keeps the position, but only requires a very small touch to release and move. Over time, it has absorbed some of the lubricant, so when folded on the bed column, it has sufficient viscosity without having to be bound.
The rope and curtains blend into one, so it's easy to take pictures with photos. To ensure safety during the shoot, I added an extra knot, but when I used it, it was just a ring around the bedpost. So all I have to do is to operate with one hand, just move the wires up or down as needed, which may only take about an inch or more.
Your sex doll
can move up and down, swing forward or backward, bend your hips or straighten, and stretch your legs or get close to what you want. The stockings are easy to slide on the sheets. Once your doll is positioned and balanced, especially in a face-to-face position, the rope can be removed from her neck to make the experience more realistic. But it does require practice and understanding of her performance at that location and where to safely position the arms and hands.
In my experience, you cannot use a bungee cord instead of a pulley rope. Instead, use the pulley rope as usual and secure a heavy rope between the ceiling hook and pulley system. It's easier to control a variety of private positions in this way.
Make sure the ceiling hooks are securely fastened to a strong point on the ceiling. I screwed me into one of the hardwood frames on the roof. It means not to enter the roof space, find its exact location and drill holes. If your frame is not where you want it, you can choose to pin the cross frame to an existing frame and use it.
The bottom line is just to get a general idea and adapt to your own personal situation and set it up, which may seem completely different from others. Hope this helps.