Hi Brit...
I've had chickens for years, and it was always a disaster when I fed them outside in their run. They are bound to spill, and whether it's sand or dirt or rocks, that feed stinks up a storm when it gets rotton and it is dangerous to your chickens if they eat rotten food. -
And when you gotta clean that rotten food up, you gotta scrape it up with a shovel and it's just NASTY!
So, I always use hanging feeders in the coop, and a bucket of water inside the coop, and outside in the run, another bucket of water.
No more stinky food problems.
And, sand is the very best chicken material I have found for the chicken run outside. No mud and it drains well, and you can rake out the poo.
Yes, sand is awesome! Go for it!