Can I use this as a tractor/coop for 2 chickens?

Sure you could. I would ultimately not want my chickens in that all the time. I would use it more for a temporary structure till I was able to supply them with something bigger. Each bird really needs at least 10 sf a piece of grazing area.

 

I would think you'd need to cover all of the roof, and overlap even, as that small of a pen would not allow them a place to escape blowing rain. And I would definitely want something quite a bit bigger by the time they were 12 weeks or so, as even the largest (other than dane size) dog pens I know of are only about 8 sq. feet, and as was already mentioned, you want to have close to 10 sq. ft EACH of run/grazing room for standard chickens. Now if you were talking a really small sized bantam breed, it would be more doable.

 

Maybe add plywood on a couple sides to close in a corner, some place the hens can retreat to and feel safer if predators come around.

 

Is that 4x6? Looks like it might be. If it is, then it could work for a couple chickens. However you will see pretty quick that they will want a bigger run. Any chance they can free range the yard?
You could convert it to a coop pretty easily by adding some weather protection. I would imagine that down in Florida they would really only sleep and lay eggs in the coop so you can probably get away with a smallish coop.

If it is only 2x3 then it would be too small except for temporary use a few hours a day or as a coop with attached run.

 

I used this exact crate for my bantams when they first arrived and for about 2 months of their growth. I tarped the sides and roof to protect them from the sun beating on them all day. I found mine on Craigslist for $50. Is my memory correct, in that if you found another used crate, you could drop down one wall on each crate and hook the two crates together, thereby enlarging the place for them? Then there would be better room for them AND the food AND the water AND the nest? Just a thought.

Lee