Good to know about the ramp, it just wastes floor space. The roost is about 12"from the wall, but I might just run one roost bar the 8 feet across the front and then shift the nesting box to where the door will be instead of adding a egg door.
Having Silkies, bantams, or old or feeble hens would be the only reason to need a ramp. I had two Silkies in the flock so we kept the ramp. Occasionally our Ameraucana used it just because she could. She's always been a wary kooky spooky type and likes the secure footing going up or down from the nestboxes.
OUR OLD LITTLE 4x6 COOP - WE LEFT THE RAMP ON & IT SURPRISED US HOW OFTEN THE CHICKENS USED IT.