I am preparing to install a small number of electrical outlet and switch boxes in stress skin panels, the type with drywall on the inner face. I understand that a router can be used to cut uniform holes. Is there a recommended bit for this purpose?

From my own experience a Dremel or Roto-Zip with a plunge bit is designed just for this purpose.
Much lighter and easier to control than most plunge routers.
Work safe, have fun.
deralte