This slide switch is a nice small one for your project. It is single-pole, double-throw and comes in a PCB mount.
You have your choice of two post lengths. The short one is 5mm and the long one is 8mm where you need that extra reach. The long post version is pictured.
Slide Switch, SPDT by Provide Your Own is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.