@Andrew Bluett-Duncan said:
You could hinge the switch on a loose heeled turnout with a nut soldered to the underside of the sleeper and bolt through from the top. Then solder the switch to the top of the bolt. There’s abit more detail on my post on Templot Forum Track Building Yeovil Pen Mill in EM.
Another way of doing it is to use a Brook-Smith-style rivet in the heel timber and solder the switch rail to that.