As you see, they will settle 35 feet up. That colony did, so 30 should be fine.
Things to remember......
They work best 100 to 1000 feet away from mother colony.
10 feet away may be passed by.
They should have the entrance facing south to east.
An empty 10 frame hive weighs approx. 35 lb. A large swarm can gather 60 lb. of honey in a week during a good flow. That puts the box, bottom, lid, and contents weighing over a hundred lbs. a week or a little more after they move in.