I know a lot of people use nucs for catching swarms, but many swarms are too large for a nuc so they don't get caught. If it was me, I'd use a deep box for the swarm trap. Most swams like to land 6 to 10 to 15 feet up in a tree, so if you have the ability to hang a box that high up, that's what I'd do. Check on it once every couple of weeks or a month is fine. If you get one, then remove the box and place it in your beeyard at dusk.
I've been keeping a few hives for the past 20-25 years, and no longer treatment free as I got tired of the losses.