New Cinder Block Smoker Plans- Looking for suggestions for doors/roof/anything else you might see

1. My plan is to use standard 8x8x16 cinder blocks and 8x8x8 cinder blocks to complete this project. I will run two ducts from the firebox to the smoke chamber. I will have one door to the smoke chamber and one door to the firebox. The firebox will have an air inlet and outlet duct with damper.

2. The smoke chamber will have two smoke ducts coming into the smoke chamber through a block that will be flipped over from the firebox to the smoke chamber room. from there I will have racks built on the inside and a smoke outlet duct on the roof.

3. I am also going to make the option to have a hot smoke capability with a lp burner on the bottom of the smoke chamber. The lp line will be piped into the smoke chamber and will be controlled by a pilot valve burner and main burner assembly with a digital controller. I have used this type of system before and it works well.

4. My questions are what do you guys suggest for a floor. I will not be smoking much over 300 degrees at all. Will I get by with just a concrete slab? What should I do for a door? Any suggestions for the roof? Is there anything that I am not thinking of?

I have a sketch here that I drew up. Any suggestions/feedback would be appreciated.