To take the second link should be the advise after seeing this.
A simple additional security feature is a flexible wire between both chains:
In red measured at widest chain angle:
In this imaginary sled the Z back supports are triangles, so ICE the wire would hit the spindle.
Strategically placed catch hooks can solve this.
After seeing a picture of a sled torn into 2 pieces back in the bracket days I had this for a few days 
