For putting out a swarm trap though, you might consider running a couple screws up through the base and into the box.
Not all swarm trap locations are as stable as sitting on top of a couple cinder blocks, so you might have some lateral movement between the parts if you don’t tack them together.
I use 5 frame Coates nucs for traps, so the only “movable parts” are the disc entrance, and the migratory top. By throwing a strap around the nuc’s “waist” I hold it tight against the top, and the cleats keep them from moving fore and aft.
I’ve considered using “double deep” nucs as well, and placing some sort of cleat on the 4 sides, to somewhat stabilize the joint between the boxes. Others accomplish this by building them double deep from the start, and only having frames in the top.