Your flock is beautiful
I have a run that is part sand and part deep litter. We have occasional wind driven flooding so our original covered 12x6 run is 6" of sand. Pro- it drains very quickly. Con- I scoop it at least twice a day to keep up with the poop (my flock free ranges much of the day as well). I wouldn't want a larger area of sand, it is just too much work.
The new area,uncovered 12x12, is deep litter. We use a mix of shavings, chunky pine bark, hay and pine needles, periodically adding more of what ever we have around. As the bedding gets deeper, there is much less mess and no smell. It also is starting to drain quicker with deeper bedding. We won't be removing the sand from the original run, but I will never create a sand based run again.
I do however, love the sand/PDZ mix I use on the poop boards in our larger coop. I would add some kind of lip to your boards and use that instead of shavings.
Your coop will also stay cleaner if you can move the food and water out into the run. We built a "table" in the uncovered portion of our run to protect the food from the rain.

I have a run that is part sand and part deep litter. We have occasional wind driven flooding so our original covered 12x6 run is 6" of sand. Pro- it drains very quickly. Con- I scoop it at least twice a day to keep up with the poop (my flock free ranges much of the day as well). I wouldn't want a larger area of sand, it is just too much work.
The new area,uncovered 12x12, is deep litter. We use a mix of shavings, chunky pine bark, hay and pine needles, periodically adding more of what ever we have around. As the bedding gets deeper, there is much less mess and no smell. It also is starting to drain quicker with deeper bedding. We won't be removing the sand from the original run, but I will never create a sand based run again.
I do however, love the sand/PDZ mix I use on the poop boards in our larger coop. I would add some kind of lip to your boards and use that instead of shavings.
Your coop will also stay cleaner if you can move the food and water out into the run. We built a "table" in the uncovered portion of our run to protect the food from the rain.