My friends trailer had everything stripped off so there are no logos. Some of them show up at vintage trailer rallies. I will keep an eye out for one and get a good picture. There is a small rally next month in Ojai and one may show up. There are always a few at the Pismo Beach rally in May.
FYI: the small Cardinals like yours were made by Adams Trailer Co in El Monte, CA.
Cardinal Industries was Indiana and made the very large trailers.
They were two separate companies.
The information and photos etc I have came from Juergen Eichenmueller.
You can find some his stuff here:
http://search.ebay.com/_W0QQsassZtrailer-dealerQQhtZ-1
Order some CD that looks interesting and ask him to add any Cardinal information. He used to do that for free. There was not a lot of Cardinal stuff when I ordered mine but he may have added more since then.
EDIT: You may find some help here:
http://groups.yahoo.com/group/vintagecardinal/