For both the log and rock you can put moss in them to make them feel smaller and therefore make the snake feel more secure. During a shed you can dampen the moss to create a humid hide. Doing that alone gave me perfect sheds with my Ball in a screen top tank, partially covered.

For the log I would also suggest backing it up to one of the walls and placing thick paper on the outside to make the log more of a cave. Also stuffing moss in the back and the front can help but covering the opening from the outside is a great way to make the log feel more secure.

Then the towel on the screen is common but it holds humidity and if you are making it wet during shed it will rust the screen. For the longest I used cardboard I cut to shape and then covered with foil. I had the windows I needed for my heat sources and was good. Then if I need to take it off it simply would lift off. Now being in a snake room I don't use it any more as I have a humidifier for the entire room.

This is the moss I have always used and have enjoyed.

https://www.amazon.com/Zoo-Med-Terra...042nst800sr-20