Clint, what top box did you have? I ask because I had structural failure with two Shad top boxes I'd bought from Twisted Throttle. The first one cracked across the bottom between the two front tabs and I realized that it was broken after I got home from a fast trip to Texas for my ex-father-in-law's funeral. Twisted Throttle replaced it but suggested that I had probably overloaded it. Hmmm.... well, maybe I did.
I kept right on loading the 2nd Shad top box the way I loaded the first one and the Givi top box I had before that on my two Kawasaki Concours. When I was in Bay St Lawrence, Nova Scotia, during my Epic Ride in 2013, I realized that the 2nd Shad was cracked in the same way and jury rigged some bungee cords to keep it from coming off the bike, knowing that I was going to be at Twisted Throttle in about a week.
When I got there, they once again told me that I had the top box overloaded. I bought a Givi E-55 and loaded it the same way since I was nearly 2000 miles from home. I've kept right on loading the Givi the same way and it's still OK.
I recognize that I've probably just signed the Givi's death warrant by saying that about it.