Coop help?

Need your help all you chicken mamas, if you can spare a few seconds to reply!

Here's the inside of my coop. The current roosts and the hanging feeder are temporary since I plan to keep the feed/water outside. See the shelf in the back of the coop? I was thinking about making the roosts above the shelf (since it is closer to the top of the coop, heat rises and we live in chilly climate). The shelf has linoleum on it now and I could dust it with DE or some sand to make scooping up the poop easier. I'd probably do that 2-3x a week...ish? I could put a 2x4 across the front to keep droppings and sand from spilling down below onto the litter. Their roosting boxes will be under the shelf, raised up about 18", also creating more floor space instead of taking up precious room for them to walk around. My question is how will the girls get up to their roosts and get down again? I want something installed in the coop that can be moved around or taken out so cleaning out the litter will be easy (as will spreading more litter and DE). I guess I just need some suggestions on placement of a ladder for them to climb or something of the sort. If you look at the left wall of the coop, there is a piece of board attached to the wall with hinges, and it can be swung upward; if something were placed underneath it, like a pole, I think it would be a nice halfway point for the girls to jump to and then jump up top, but I don't know if full size birds can jump and flap up that high safely. Help!

So the plan is now to have the nesting boxes on the right wall to the left of the window (so no direct light shines in them), raise that plank with the hinges as a springboard to the shelf, and have 2 roosting bars up there. I might put another shelf underneath that for supplies like litter and DM, etc, and cover it with something to keep them out of there. 

Sounds good!  We have a roosting bar going across the length our coop just under the peak.  Ours seem to like to get as high as possible and they have no problem flying up.  They are strong enough to fly into the very high rafters in our barn (20+ft up?). The only issue might be if they have enough room in the coop to get lift-off I guess.