There are a few things to be aware of besides strengthening the back side of the mount.
The Hustler ballmount is flimsy at best. The two halves are stamped stainless steel, and the rolled ferrule which holds the sides apart when you tighten the cross bolt is not welded. So, if you tighten it too much, the ferrule splits apart, which loosens the ball, and the antenna falls over. It is just barely adequate for the smaller coils.
The fold over mast's hinge isn't very sturdy, and after a while the hinge loosens and causes an intermittent connection. This is why you see so many of them with a copper strap across the hinge.
Which ever mast you use, don't over tighten the coil. It is held on by just 5 threads which is bad enough. But, when you over tighten them, the pressed in threaded post loosens, with predictable results.
In spite of their problems (until just recently), it's been the most popular HF mobile antenna. High Sierra now has that honor.