It was likely not the way you loaded it but rather the inadequate/low quality factory leaf springs that Voltage or more specifically Lippert specs for our trailersóespecially us two axle guys.
Several of us have replaced them. If you do a search you can find a few threads on this exact issue.
I had mine replaced with 7 leaf American made springs by Triangle. They are manufactured in Fontana, CA and they are far superior to the Chinese garbage our trailers come with. Another member went with 8 leaf springs on his rig from the same manufacturer.
Again, this is way too common on the two axle 40í foot toy haulers. The 3-axle trailers donít seem to have this issue as the load is better distributed across an additional axle and another set of leafs. Also, many replace the shackles and bolts with heavier grade stuff.
I do not recommend the wet bolt replacement set up either as they donít seem up to the task on the three axle trailers. For that matter you probably need to avoid truck tires too as they donít seem to have the load capacity as the proper trailer tires.
Notice the difference in the factory spring and the one from Triangle I replaced it with (all four). Only one more leaf bit a much greater arc. Two and a half years later and they are holding up well.