3D printing alone is insufficient for these weights and mounting requirements..
Not entirely true. There are several materials that can significantly increase strength, multiple ways to print the parts, and you can always redesign them to be much more rigid and durable — this is especially important.
I’ve tested at least five different BTA solutions in PETG, and they worked decently. However, when I switched to Tritan HT, the performance improved considerably.
That said, exposing the parts to direct sunlight (for example, during a transition) will definitely hurt their longevity.
For an extra level of safety, you can coat the 3D printed part with resin — much like a carbon fiber + resin composite, but without the carbon. This usually turns the part into something extremely sturdy.