Thank you for the recommendation. I ended up using those support arms, but I used my own 2” pole since I preferred my bottom enclosure to be aligned vertically and immediately under the top enclosure, and since my eave is not long enough to accommodate a J mount bracket or even an under-eave mount bracket. It just seemed more appropriate to use a straight pole since I’m mounting one enclosure on top of another. But I hope it is sturdy enough with my own pole and that flimsy Wilson bracket on my eave... it sure feels like it’s not going to budge though. Here is an updated picture:
For future readers, the support arms are compatible only with a 2” pole. I had to swap my original one because it was only 1.5”. Mine is 3 feet long.