I use chicken watering cups attached to 3/4" PVC, fed by a 275 gallon water tote. Obviously not portable, but the consistent recommend has been 1 cup per 5 birds, maximum - and that they aren't suitable for larger birds (like my ducks, for whom I use an automatic dog watering bowl, which could also be fed from a 5 gal bucket.)
In a hoop house of 10-12, I'd go three watering cups, and be aware that the birds will perch on the pvc feeder pipe, so be sure you have a way to support it if you go that route. If attaching multiple cups straight to the bucket (I'd go this route, 3 cups at 90 degrees to one another - left, center, right, none in the "back"), and have something to set the bucket on to raise it off the ground some. Target height (again, according to the mfg of my cups) was about 6" off the ground. If you hoop coops are semi stationary, I'd set the bucket on an upturned half cmu - the hollow core concrete blocks about 8" on a side you can buy at the big box for around $2-3/block. Then I'd surround that with a bag of river rocks, not pea gravel, so the chicks don't stand in the water they will inevitably splash, to reduce mess when a leak eventually develops, and to hit your 6" target height. Those are $5 a bag, you will probably want two, they are only half a cu ft each.
Hope that helps!