I have several hutch type coops, and if I'm not misreading your post, that is what you are planning. It seems to me that 1 1/2 feet off the ground is a bit short. I planned mine so that it is at the appropriate height for me to lean into to clean it. If it weren't raining right now, I'd go out and measure, but then again, that might not be helpful, since I'm kinda short.
Also, it seems that 4 feet wide is a bit of a stretch for cleaning. Again, your arms may be longer than mine!
The dimensions of my coops are 3' X 7'. That way they fit perfectly under a 4 X 8 sheet of plywood for the roof. The 21 square feet provided comfortably houses 7 chickens. Here is a picture. The pop door is in the middle, and on either side are big doors that open so I can lean in and clean the whole thing easily.
The coop itself is about 4 feet tall on the front, and 3 1/2 feet tall on the back. It has a double decker nestbox in one corner, and a roost that stretches from the nestbox to the other side of the coop. The roost isn't very high off the floor, maybe a foot, maybe less. And about a foot off the back wall.
I have a window on the east side which is covered in hardware cloth in the summer, and by a wood panel over that in the winter. I don't have one on the west side, because we get rain from that direction quite often. It is hot here in the summers, but probably not as hot as your summers. You might need more ventillation than I do. I always keep one coop door open in the summer during the day also. It would probably help you to situate the coop so that the front is facing north, or east. And of course, to take advantage of any shade that you might have when you decide where to put the coop. Our run has no shade at all.
The floor is wood covered in wood shavings.
Well, I hope that was helpful to you. I really like the design, and have built 2 just like that. The first coop we built wasn't designed nearly as well, so I tried to learn from my mistakes as I expanded. My biggest mistakes were that I couldn't easily reach the back corners on the first coop, and that I put the nestboxes on the outside, where heavy rains could get in from time to time. Wet bedding, Yuck! I've had to do a lot of reconfiguring on that first coop to make it practical. But you live and learn!