Have the homeowner install a piece of casing that has been trimmed enough to allow the installation of a standard cover.
After the inspection, replace the casing and receptacle cover.
You didn't get this idea from me.
BTW, would a metal handy box cover fill the bill?
Or, since dry location receptacle covers are not required to be listed (as far as I know), trim an unlisted cover. Of course, this will probably really get the inspector mad.
[This message has been edited by Tom (edited 12-10-2002).]