Isn't there a 12v power outlet in the boot? Doesn't that have a cover on it? I know what kind of over you are referring to as the Mini used to do a Smokers and Non Smokers package which replaced the cigar lighter with a cover, but it also had a 12v socket in the book which also had a blank socket cover on it.
If the one in the Civic boot has a cover then more than likely this will fit to the one inside the cabin
OR you could be like some of us on here and replace the lighter with a torch