The first thing I see for improvement is putting a 3 to 4 inch lip on bottom of nest front to keep in straw, hay or shavings.
No partitions is called a community nest. Some have successfully used this type. I have never heard of it not working.
As far as pingpong balls, I agree with others that something heavier is better.
Myself all Ceramic eggs are white as I keep brown egg layers.
I've always kept Ceramic eggs in nests, only to remove if they need a washing.
Golf balls work, from what I've read, but never used them.
I also don't disturb a hen laying on a nest.
Curtains I've never used, lights in my coops are above nests and don't shine inside.
View attachment 2796862
GC