Thank you for the advice.
It was printed with 20% Infill, walls were the default for 0.2 layer size and I didn't change the wall count.
One thing I was thinking of trying is changing the infill pattern to perhaps the Gyro or SubD Cubic which might give it a more flexible infill or the wavelength shape.
I've only printed one so far, and I got some more coming which will be slightly different, I added 2MM to the part that's cracking and reinforced the overall bottom.
I'm using a co-workers printer, mine is coming on Friday, I'm getting the Monoprice Ultimate II and then I'll be able to experiment as much as I want with different settings.
The part only has to snap onto the rail once, it won't be removed and reinstalled unless it comes off for some reason.
But I think you are right, I was looking at it again in Cura and I think adding walls would help more than increasing infill due to the space in those cylinder shapes.