How to make a clean out door?

[hokankai]

I'm converting a 4x4 dog house into a banty coop, and I'm having trouble planning out how to make the clean out door. My plan is to make the entire back wall a door, but I'm not sure how to go about doing it. Do you just use a saw to cut out the hole in the wall and use it as the door? We did that for our egg door on the main coop and it's flush with the wall...but there are tiny gaps in the wall where it was filed down so the door would hinge open and closed. I'm also worried about it warping as the dog house is made out of OSB.

Also, I'm thinking it would be a good idea to make a slide out floor, but I have NO idea how to do that, haha. Any ideas?

Here's what I wanted to do, but I just don't know how to go about doing it carpentry/hardware-wise.

 

[atr04screw]

Instead of cutting a hole out of the back wall, it would be easier and work better to just take the back wall off and make two small doors to replace the wall. I assume you want to make the wall plywood and not wire, so you need to cut the plywood out to fit in the hole with about 1/4"-1/2" of space on all sides so that it can swell and still open. Also, use two hinges on each door so that it doesn't twist. For the doors, if you go with thinner plywood like 3/8" or 1/2", you might want to frame them with 2x2 on the inside so they dont warp. For slide out trays, you can buy the plastic trays made to go under a washer/dryer and put them down. I was originally going to do that, but I ended up putting plywood down and covered it with linoleum that I can just hose off.