Hi Springview, this will be the second time we have "met" I am not sure Charliehorse read your question real well. No offense Charlie. If you are building a fight pen it will, more than likely be on the ground. Therefore, you do not need a floor.
Cleaning the area is not a big concern if the pen is large enough to hold that many birds.
Mine is 24 X 18, with a 6ft/ 1 inch mesh top. Use 1 inch mesh netting; younger birds will fly right through 2 inch. ( I hatched and raised 300 XLD1's last season.)
Giving the birds the option of shelter is a good idea, branches from evergreens, the top of an old dog kennel,or a tarp are all fine. I throw straw to my Pheasant breeder stock, it keeps them warm and they enjoy scratching and kicking it around.
Lastly, collect eggs daily, just like Charliehorse said. You want eggs as fresh as possible.
Oh, and
, the Ghost.