Does anyone hang nest boxes under the poop board?
I use the area under my DB for chicks. With removable wire screens I make that their brooding area on up until they’re integrated.
Is the slanted top advice specifically so they don't sleep there at night, or in general?
Pretty much. In my big coop I built a flat top on my nests, mainly because I wanted the flat surface on MY side of the coop and I have had a never ending battle of teaching the newly integrated birds to sleep on the roosts (even though they’re higher).
Just a note: There is that rule of giving each bird 8-12” of space on the roost and that works well...on paper, that is. When I built my coop that is exactly what I did. Built enough linear feet of roost based on the number of birds I wanted. However, and this is a biggie, one foot/bird
is not enough when the younger birds start roosting. Three feet isn’t enough some nights. That’s where my flat topped nest boxes come into play. The 6 month old girls are still terrified of the older girls. And I’m certain those pecks don’t feel good.
Here is a picture of my nest boxes. I keep netting secured over it on the birds’ side. Netting is also used over the nest holes to deter the untrained youngsters and aggravating broodies at night, when needed. Also, my roosts have been raised since this picture was taken, which has caused another problem.
I still need to tweak the inside of the coop. You know you never truly finish, don’t you?

I am going to lower my nest boxes so I can lower my roosts a tad. The reason being I did not allow enough flight room for the birds to be able to safely jump from the DB. Should be a 45* angle and mine falls short and only my big old really fluffy birds (BO and Cochin) use the ramp down in the mornings.
And also, I don’t think I ever gave
@aart credit for using her nest box design. Thank you aart! I loved your nest box design and now I love mine.

My coop was built using several coop inspirations.