Thank you Jordan. Yes the blades stay against the stock rails. The Caboose Hobbies ground throw have an internal spring. That's very useful. But with the switch to change the polarity of the frog, it's not important if the blade don't make a contact. That's the switch which works. The electricity contact is reliable. I do that on all of my layouts from N to O.
I've tried to make something simple and reliable for years but I need to have access for future maintenance.
I begin by choosing a small nice piece of 5 mm plywood
I don't use small screws to fix the switch: I use a copper wire. It's stronger because the screws have only 5 mm thickness.
On the back, I solder the two copper ends together.
I use two pieces of a brass tube and some code 100 rail, soldered together. I fix this part with metal wire and solder like the switch.
And I use a code 75 rail and a square piece of 1 mm rod to make the slider
The rod will be connected in the PCB between the blades.
I make long holes to screw the piece under the layout.
The code 75 rail push the switch and the frog will change of polarity.
Once installed and adjusted, I've just to connect the 2 stock rail feeders (L and R) and the frog on the common.