If you want a real good answer to that question about mice...call an exterminator and you may hear a lot of laughing! I seriously doubt lights will keep them out, in fact it might show them the way home! Light or no lights...mice are always looking for a home to nest in.
A few solar lights near the door or some set on the dash in a MH are nice. This time of year folks get all cheery and want lights everywhere and that is fine from dusk until 10 PM then they need to be shut off so the whole campground isn't bright all night.
I realize the psychological affect of light...makes people happy and feel connected to a modern society...however even with LED lighting to save energy...what's wrong with a little natural darkness so one can see the stars!