That kinda defeats the point of ease of access(for cleaning) and not taking up floor space...and it really isn't an issue if they roost on the roost or the edge or the board itself.If you put the poop board on the bottom, very low to the floorboard
Welcome to BYC!How much head room above the Roosting Board do they need
As much as possible for ventilation up high away from head height, IMO, especially if you live in a cold climate.
Here's my take on how high stuff 'should'(works best) be:
https://www.backyardchickens.com/articles/coop-stack-up-how-high-should-stuff-be.73427/