I use MRCS MP1 v2 switches.
They are 1.5" wide, 1.5" high by .5" deep and I mount them on top of my layout right next to the turnout. I use 1/2" foam for my sub roadbed and just bury them with a thin sheet of styrene over them and add scenery materials. The throw wire (I use straightened large paperclips) can be ent to conform to the edge of your roadbed so they are virtually undetectable. You can mount them under the base layer ( I use 3/16" luan) as well with small screws.