Signals in general and searchlight signals in particular have always been a bit of a challenge in N Scale. In more recent times the availability of surface mounted (SMD) type of Light Emitting Diodes (LED) have improved the chances of getting something to scale. The development of 3D printing has made it possible to include more accurate detail parts.
Jersey Mikes Railroad Adventures blog shows the type of searchlight signals that would be common along the line in the era that I model and would be similar to what I would like to have on the layout. Below is a quick overview of three brands of searchlight signals that are available.
Layout Dynamics. These are made with brass tubing for the pole that appears to be a 1/16" diameter with all of the other parts made from 3D printing. They come fully assembled, painted, and wired with a 3 color LEDs. They are offered in 1 or 2 head versions and with or without relay cabinets.
Showcase Miniatures. The kit uses a 1/32" brass tube and detail parts of etched brass and white metal. Each kit comes with 2 signal heads and can be customized by the builder. Very tiny 3 color LED's with really fine wires can be ordered separately.
Custom Signal Systems. Here is a screen shot from the Corn Country Rails You tube channel that covers these signals quite well including their installation.
The ready to run signals are not cheap but after making a few of my own I now have an appreciation for what it takes. My reason for making my own was not so much the cost but how delicate they looked. I wanted to gain some experience handling and installing some of my own first and may be using some purchased ones in the future as they are more accurate and detailed than I can make.