An LTG member, peteybass, was once in the business of making saddles. He offered a variety of materials and notched and unnotched versions. His website
www.guildbassparts.com is no longer active.
A sample page
https://web.archive.org/web/2016101...assparts.com/www.guildbassparts.com/Home.html
My recollection is that he made a big deal that the saddles were not exactly the same across all iterations of the bridge and associated basses. I remember that since it isn't my experience.
He hasn't been around recently but if you were motivated enough you could probably track him down and he probably has some saddles. Maybe he will even share why he closed the business. His prices were higher than I wanted to pay for backups or an experiment on my part.
The only saddle I have that split seems to have done so because of downward pressure from the string. I think there was room at the top of the slider and the string pressure could push the sides of the saddle at the base of the slider apart. My first guess to prevent that would be to have the notch for the slider as short as possible.