I see you're getting a lot of views and no answers.
For the most part , coach builders source the switches from automotive and use them , in my case the ignition switch and headlight switch are from a 72/77 Chevy P/U. and can be found at any auto parts store.
Here's what mine looks like behind the dash.
If yours is different than this photo, try adding a picture of it to your post and maybe we can get you the correct part.