Maureen, you can "unofficially" enter AKC events with an unrecognized breed, as what the kennel club calls "demonstration dog." Been there, done that. But alternatives are numerous for gundogs here, with orgs. that include NAVHDA (North American Versatile Hunting Dog Assn.), NAHRA (North American Hunting Retriever Assn.) and HRC (Hunting Retriever Club) of the United Kennel Club. The latter two allow all gundog breeds in their tests, while NAVHDA is for HPRs.
I've run retriever tests with all three of these
and in NAHRA even have seen border collies and St. Bernards worked.
But never an American cocker , though there are a couple of working lines left, and I occasionally come across them at AKC spaniel tests. Spanieling in the the US has almost divided into subsets, with field-bred ESS and cockers running trials and tests to themselves, and the minor spaniels off on their own for hunt tests. (Sussex, Clumbers, Field and AWS cannot [yet] compete in field trials, nor do they have one of their own [yet] that would lump the minor breeds together.)
IWS are considered a retriever in the States and again limited to AKC retrieving events.
MG