I picked up a solar garden light from walmart. I pop the hood and trap the light in the lid so the light is under the hood and the minipanel outside it. I haven't had a problem since then, but it it could be coincidence, or my being more careful scouting for mouseholes before pitching camp.
Update: near Los Alamos/Jemez Springs, NM we had a pack rat build a nest in the engine bay right under the Rid-a-Rat between my periodic checks of the engine bay, so perhaps it doesn't work as advertised.