also the design in the second picture seems to have an issue as well. It seems that the acrylic screen/cover is used to run the sled against the fence. The piece to be routed is sticking out of the base and it has no back support (unless a sacrificial piece is used).
I am considering the below design in which the side of the sled situated next to the fence and ahead of the purple
clamp base (yellow block) is cut in such away that would not allow the bit to reach the base of the sled because there is nothing there
(that yellow block was cut out)
NO REALLY! Sorry.
In my new routing table which I am designing, there will be 2 parallel mitre slots (both with T-slots). So the runners will only have a cross-piece for hold down clamps. There will be no need of MDF nor Acrylic nor plywood or any sled of any thickness since the workpiece will be supported by the 2 mitre track runners which will be made the same level as the router table top itself.
(I bought 2 Aluminum Mitre Tracks to be precisely embedded in 2 precise parallel DADOS of correct depths to be routed out by my small CMC router.
My table top will be 38mm thick Free of Charge "sink cut-out" of a post-form kitchen worktop laminate).